{"id":1412,"date":"2024-06-02T23:00:18","date_gmt":"2024-06-02T23:00:18","guid":{"rendered":""},"modified":"2024-06-05T06:12:46","modified_gmt":"2024-06-04T22:12:46","slug":"typescript-%e4%b9%8b-object-types","status":"publish","type":"post","link":"https:\/\/www.lccc.top\/?p=1412","title":{"rendered":"TypeScript \u4e4b Object Types"},"content":{"rendered":"\n

\u524d\u8a00<\/h2>\n

TypeScript \u7684\u5b98\u65b9\u6587\u6863\u65e9\u5df2\u66f4\u65b0\uff0c\u4f46\u6211\u80fd\u627e\u5230\u7684\u4e2d\u6587\u6587\u6863\u90fd\u8fd8\u505c\u7559\u5728\u6bd4\u8f83\u8001\u7684\u7248\u672c\u3002\u6240\u4ee5\u5bf9\u5176\u4e2d\u65b0\u589e\u4ee5\u53ca\u4fee\u8ba2\u8f83\u591a\u7684\u4e00\u4e9b\u7ae0\u8282\u8fdb\u884c\u4e86\u7ffb\u8bd1\u6574\u7406\u3002<\/p>\n

\u672c\u7bc7\u6574\u7406\u81ea TypeScript Handbook \u4e2d \u300cObject Types<\/a>\u300d \u7ae0\u8282\u3002<\/p>\n

\u672c\u6587\u5e76\u4e0d\u4e25\u683c\u6309\u7167\u539f\u6587\u7ffb\u8bd1\uff0c\u5bf9\u90e8\u5206\u5185\u5bb9\u4e5f\u505a\u4e86\u89e3\u91ca\u8865\u5145\u3002<\/p>\n

\u5bf9\u8c61\u7c7b\u578b\uff08Object types\uff09<\/h2>\n

\u5728 JavaScript \u4e2d\uff0c\u6700\u57fa\u672c\u7684\u5c06\u6570\u636e\u6210\u7ec4\u548c\u5206\u53d1\u7684\u65b9\u5f0f\u5c31\u662f\u901a\u8fc7\u5bf9\u8c61\u3002\u5728 TypeScript \u4e2d\uff0c\u6211\u4eec\u901a\u8fc7\u5bf9\u8c61\u7c7b\u578b\uff08object types\uff09\u6765\u63cf\u8ff0\u5bf9\u8c61\u3002<\/p>\n

\u5bf9\u8c61\u7c7b\u578b\u53ef\u4ee5\u662f\u533f\u540d\u7684\uff1a<\/p>\n

<\/p>\n
function<\/span> greet<\/span>(<\/span>person<\/span>: {<\/span> name<\/span>: string<\/span>;<\/span> age<\/span>: number<\/span> }<\/span>)<\/span> {<\/span>\n  return<\/span> \"Hello \"<\/span> +<\/span> person<\/span>.<\/span>name<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u4e5f\u53ef\u4ee5\u4f7f\u7528\u63a5\u53e3\u8fdb\u884c\u5b9a\u4e49\uff1a<\/p>\n
<\/p>\n
interface<\/span> Person<\/span> {<\/span>\n  name<\/span>: string<\/span>;<\/span>\n  age<\/span>: number<\/span>;<\/span>\n}<\/span>\n \nfunction<\/span> greet<\/span>(<\/span>person<\/span>: Person<\/span>)<\/span> {<\/span>\n  return<\/span> \"Hello \"<\/span> +<\/span> person<\/span>.<\/span>name<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u6216\u8005\u901a\u8fc7\u7c7b\u578b\u522b\u540d\uff1a<\/p>\n
<\/p>\n
type<\/span> Person<\/span> =<\/span> {<\/span>\n  name<\/span>: string<\/span>;<\/span>\n  age<\/span>: number<\/span>;<\/span>\n}<\/span>;<\/span>\n \nfunction<\/span> greet<\/span>(<\/span>person<\/span>: Person<\/span>)<\/span> {<\/span>\n  return<\/span> \"Hello \"<\/span> +<\/span> person<\/span>.<\/span>name<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u5c5e\u6027\u4fee\u9970\u7b26\uff08Property Modifiers\uff09<\/h2>\n
\u5bf9\u8c61\u7c7b\u578b\u4e2d\u7684\u6bcf\u4e2a\u5c5e\u6027\u53ef\u4ee5\u8bf4\u660e\u5b83\u7684\u7c7b\u578b\u3001\u5c5e\u6027\u662f\u5426\u53ef\u9009\u3001\u5c5e\u6027\u662f\u5426\u53ea\u8bfb\u7b49\u4fe1\u606f\u3002<\/p>\n
\u53ef\u9009\u5c5e\u6027\uff08Optional Properties\uff09<\/h3>\n
\u6211\u4eec\u53ef\u4ee5\u5728\u5c5e\u6027\u540d\u540e\u9762\u52a0\u4e00\u4e2a ?<\/code> \u6807\u8bb0\u8868\u793a\u8fd9\u4e2a\u5c5e\u6027\u662f\u53ef\u9009\u7684\uff1a<\/p>\n
<\/p>\n
interface<\/span> PaintOptions<\/span> {<\/span>\n  shape<\/span>: Shape<\/span>;<\/span>\n  xPos<\/span>?: number<\/span>;<\/span>\n  yPos<\/span>?: number<\/span>;<\/span>\n}<\/span>\n \nfunction<\/span> paintShape<\/span>(<\/span>opts<\/span>: PaintOptions<\/span>)<\/span> {<\/span>\n  \/\/ ...<\/span>\n}<\/span>\n \nconst<\/span> shape<\/span> =<\/span> getShape<\/span>(<\/span>)<\/span>;<\/span>\npaintShape<\/span>(<\/span>{<\/span> shape }<\/span>)<\/span>;<\/span>\npaintShape<\/span>(<\/span>{<\/span> shape,<\/span> xPos<\/span>: 100<\/span> }<\/span>)<\/span>;<\/span>\npaintShape<\/span>(<\/span>{<\/span> shape,<\/span> yPos<\/span>: 100<\/span> }<\/span>)<\/span>;<\/span>\npaintShape<\/span>(<\/span>{<\/span> shape,<\/span> xPos<\/span>: 100<\/span>,<\/span> yPos<\/span>: 100<\/span> }<\/span>)<\/span>;<\/span><\/pre>\n<\/div>\n
\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0cxPos<\/code> \u548c yPos<\/code> \u5c31\u662f\u53ef\u9009\u5c5e\u6027\u3002\u56e0\u4e3a\u4ed6\u4eec\u662f\u53ef\u9009\u7684\uff0c\u6240\u4ee5\u4e0a\u9762\u6240\u6709\u7684\u8c03\u7528\u65b9\u5f0f\u90fd\u662f\u5408\u6cd5\u7684\u3002<\/p>\n
\u6211\u4eec\u4e5f\u53ef\u4ee5\u5c1d\u8bd5\u8bfb\u53d6\u8fd9\u4e9b\u5c5e\u6027\uff0c\u4f46\u5982\u679c\u6211\u4eec\u662f\u5728 strictNullChecks<\/code> \u6a21\u5f0f\u4e0b\uff0cTypeScript \u4f1a\u63d0\u793a\u6211\u4eec\uff0c\u5c5e\u6027\u503c\u53ef\u80fd\u662f undefined<\/code>\u3002<\/p>\n
<\/p>\n
function<\/span> paintShape<\/span>(<\/span>opts<\/span>: PaintOptions<\/span>)<\/span> {<\/span>\n  let<\/span> xPos<\/span> =<\/span> opts<\/span>.<\/span>xPos<\/span>;<\/span>              \n  \/\/ (property) PaintOptions.xPos?: number | undefined<\/span>\n  let<\/span> yPos<\/span> =<\/span> opts<\/span>.<\/span>yPos<\/span>;<\/span>\n  \/\/ (property) PaintOptions.yPos?: number | undefined<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u5728 JavaScript \u4e2d\uff0c\u5982\u679c\u4e00\u4e2a\u5c5e\u6027\u503c\u6ca1\u6709\u88ab\u8bbe\u7f6e\uff0c\u6211\u4eec\u83b7\u53d6\u4f1a\u5f97\u5230 undefined<\/code> \u3002\u6240\u4ee5\u6211\u4eec\u53ef\u4ee5\u9488\u5bf9 undefined<\/code> \u7279\u6b8a\u5904\u7406\u4e00\u4e0b\uff1a<\/p>\n
<\/p>\n
function<\/span> paintShape<\/span>(<\/span>opts<\/span>: PaintOptions<\/span>)<\/span> {<\/span>\n  let<\/span> xPos<\/span> =<\/span> opts<\/span>.<\/span>xPos<\/span> ===<\/span> undefined<\/span> ? 0<\/span> : opts<\/span>.<\/span>xPos<\/span>;<\/span>\n  \/\/ let xPos: number<\/span>\n  let<\/span> yPos<\/span> =<\/span> opts<\/span>.<\/span>yPos<\/span> ===<\/span> undefined<\/span> ? 0<\/span> : opts<\/span>.<\/span>yPos<\/span>;<\/span>\n  \/\/ let yPos: number<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u8fd9\u79cd\u5224\u65ad\u5728 JavaScript \u4e2d\u5f88\u5e38\u89c1\uff0c\u4ee5\u81f3\u4e8e\u63d0\u4f9b\u4e86\u4e13\u95e8\u7684\u8bed\u6cd5\u7cd6\uff1a<\/p>\n
<\/p>\n
function<\/span> paintShape<\/span>(<\/span>{<\/span> shape,<\/span> xPos =<\/span> 0<\/span>,<\/span> yPos =<\/span> 0<\/span> }<\/span>: PaintOptions<\/span>)<\/span> {<\/span>\n  console<\/span>.<\/span>log<\/span>(<\/span>\"x coordinate at\"<\/span>,<\/span> xPos<\/span>)<\/span>;<\/span> \/\/ (parameter) xPos: number<\/span>\n  console<\/span>.<\/span>log<\/span>(<\/span>\"y coordinate at\"<\/span>,<\/span> yPos<\/span>)<\/span>;<\/span> \/\/ (parameter) yPos: number<\/span>\n  \/\/ ...<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u8fd9\u91cc\u6211\u4eec\u4f7f\u7528\u4e86\u89e3\u6784\u8bed\u6cd5\u4ee5\u53ca\u4e3a xPos<\/code> \u548c yPos<\/code> \u63d0\u4f9b\u4e86\u9ed8\u8ba4\u503c\u3002\u73b0\u5728 xPos<\/code> \u548c yPos<\/code> \u7684\u503c\u5728 paintShape<\/code> \u51fd\u6570\u5185\u90e8\u4e00\u5b9a\u5b58\u5728\uff0c\u4f46\u5bf9\u4e8e paintShape<\/code> \u7684\u8c03\u7528\u8005\u6765\u8bf4\uff0c\u5374\u662f\u53ef\u9009\u7684\u3002<\/p>\n
\n
\u6ce8\u610f\u73b0\u5728\u5e76\u6ca1\u6709\u5728\u89e3\u6784\u8bed\u6cd5\u91cc\u653e\u7f6e\u7c7b\u578b\u6ce8\u89e3\u7684\u65b9\u5f0f\u3002\u8fd9\u662f\u56e0\u4e3a\u5728 JavaScript \u4e2d\uff0c\u4e0b\u9762\u7684\u8bed\u6cd5\u4ee3\u8868\u7684\u610f\u601d\u5b8c\u5168\u4e0d\u540c\u3002<\/p>\n<\/blockquote>\n
<\/p>\n
function<\/span> draw<\/span>(<\/span>{<\/span> shape<\/span>: Shape<\/span>,<\/span> xPos<\/span>: number<\/span> =<\/span> 100<\/span> \/*...*\/<\/span> }<\/span>)<\/span> {<\/span>\n  render<\/span>(<\/span>shape<\/span>)<\/span>;<\/span>\n  \/\/ Cannot find name 'shape'. Did you mean 'Shape'?<\/span>\n  render<\/span>(<\/span>xPos<\/span>)<\/span>;<\/span>\n  \/\/ Cannot find name 'xPos'.<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u5728\u5bf9\u8c61\u89e3\u6784\u8bed\u6cd5\u4e2d\uff0cshape: Shape<\/code> \u8868\u793a\u7684\u662f\u628a shape<\/code> \u7684\u503c\u8d4b\u503c\u7ed9\u5c40\u90e8\u53d8\u91cf Shape<\/code>\u3002 xPos: number<\/code> \u4e5f\u662f\u4e00\u6837\uff0c\u4f1a\u57fa\u4e8e xPos<\/code> \u521b\u5efa\u4e00\u4e2a\u540d\u4e3a number<\/code> \u7684\u53d8\u91cf\u3002<\/p>\n
readonly<\/code> \u5c5e\u6027\uff08readonly Properties\uff09<\/h3>\n
\u5728 TypeScript \u4e2d\uff0c\u5c5e\u6027\u53ef\u4ee5\u88ab\u6807\u8bb0\u4e3a readonly<\/code>\uff0c\u8fd9\u4e0d\u4f1a\u6539\u53d8\u4efb\u4f55\u8fd0\u884c\u65f6\u7684\u884c\u4e3a\uff0c\u4f46\u5728\u7c7b\u578b\u68c0\u67e5\u7684\u65f6\u5019\uff0c\u4e00\u4e2a\u6807\u8bb0\u4e3a readonly<\/code>\u7684\u5c5e\u6027\u662f\u4e0d\u80fd\u88ab\u5199\u5165\u7684\u3002<\/p>\n
<\/p>\n
interface<\/span> SomeType<\/span> {<\/span>\n  readonly<\/span> prop<\/span>: string<\/span>;<\/span>\n}<\/span>\n \nfunction<\/span> doSomething<\/span>(<\/span>obj<\/span>: SomeType<\/span>)<\/span> {<\/span>\n  \/\/ We can read from 'obj.prop'.<\/span>\n  console<\/span>.<\/span>log<\/span>(<\/span>`prop has the value '${<\/span>obj<\/span>.<\/span>prop<\/span>}<\/span><\/span>'.`<\/span>)<\/span>;<\/span>\n \n  \/\/ But we can't re-assign it.<\/span>\n  obj<\/span>.<\/span>prop<\/span> =<\/span> \"hello\"<\/span>;<\/span>\n  \/\/ Cannot assign to 'prop' because it is a read-only property.<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u4e0d\u8fc7\u4f7f\u7528 readonly<\/code> \u5e76\u4e0d\u610f\u5473\u7740\u4e00\u4e2a\u503c\u5c31\u5b8c\u5168\u662f\u4e0d\u53d8\u7684\uff0c\u4ea6\u6216\u8005\u8bf4\uff0c\u5185\u90e8\u7684\u5185\u5bb9\u662f\u4e0d\u80fd\u53d8\u7684\u3002readonly<\/code> \u4ec5\u4ec5\u8868\u660e\u5c5e\u6027\u672c\u8eab\u662f\u4e0d\u80fd\u88ab\u91cd\u65b0\u5199\u5165\u7684\u3002<\/p>\n
<\/p>\n
interface<\/span> Home<\/span> {<\/span>\n  readonly<\/span> resident<\/span>: {<\/span> name<\/span>: string<\/span>;<\/span> age<\/span>: number<\/span> }<\/span>;<\/span>\n}<\/span>\n \nfunction<\/span> visitForBirthday<\/span>(<\/span>home<\/span>: Home<\/span>)<\/span> {<\/span>\n  \/\/ We can read and update properties from 'home.resident'.<\/span>\n  console<\/span>.<\/span>log<\/span>(<\/span>`Happy birthday ${<\/span>home<\/span>.<\/span>resident<\/span>.<\/span>name<\/span>}<\/span><\/span>!`<\/span>)<\/span>;<\/span>\n  home<\/span>.<\/span>resident<\/span>.<\/span>age<\/span>++<\/span>;<\/span>\n}<\/span>\n \nfunction<\/span> evict<\/span>(<\/span>home<\/span>: Home<\/span>)<\/span> {<\/span>\n  \/\/ But we can't write to the 'resident' property itself on a 'Home'.<\/span>\n  home<\/span>.<\/span>resident<\/span> =<\/span> {<\/span>\n  \/\/ Cannot assign to 'resident' because it is a read-only property.<\/span>\n    name<\/span>: \"Victor the Evictor\"<\/span>,<\/span>\n    age<\/span>: 42<\/span>,<\/span>\n  }<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
TypeScript \u5728\u68c0\u67e5\u4e24\u4e2a\u7c7b\u578b\u662f\u5426\u517c\u5bb9\u7684\u65f6\u5019\uff0c\u5e76\u4e0d\u4f1a\u8003\u8651\u4e24\u4e2a\u7c7b\u578b\u91cc\u7684\u5c5e\u6027\u662f\u5426\u662f \treadonly<\/code>\uff0c\u8fd9\u5c31\u610f\u5473\u7740\uff0creadonly<\/code> \u7684\u503c\u662f\u53ef\u4ee5\u901a\u8fc7\u522b\u540d\u4fee\u6539\u7684\u3002<\/p>\n
<\/p>\n
interface<\/span> Person<\/span> {<\/span>\n  name<\/span>: string<\/span>;<\/span>\n  age<\/span>: number<\/span>;<\/span>\n}<\/span>\n \ninterface<\/span> ReadonlyPerson<\/span> {<\/span>\n  readonly<\/span> name<\/span>: string<\/span>;<\/span>\n  readonly<\/span> age<\/span>: number<\/span>;<\/span>\n}<\/span>\n \nlet<\/span> writablePerson<\/span>: Person<\/span> =<\/span> {<\/span>\n  name<\/span>: \"Person McPersonface\"<\/span>,<\/span>\n  age<\/span>: 42<\/span>,<\/span>\n}<\/span>;<\/span>\n \n\/\/ works<\/span>\nlet<\/span> readonlyPerson<\/span>: ReadonlyPerson<\/span> =<\/span> writablePerson<\/span>;<\/span>\n \nconsole<\/span>.<\/span>log<\/span>(<\/span>readonlyPerson<\/span>.<\/span>age<\/span>)<\/span>;<\/span> \/\/ prints '42'<\/span>\nwritablePerson<\/span>.<\/span>age<\/span>++<\/span>;<\/span>\nconsole<\/span>.<\/span>log<\/span>(<\/span>readonlyPerson<\/span>.<\/span>age<\/span>)<\/span>;<\/span> \/\/ prints '43'<\/span><\/pre>\n<\/div>\n
\u7d22\u5f15\u7b7e\u540d\uff08Index Signatures\uff09<\/h3>\n
\u6709\u7684\u65f6\u5019\uff0c\u4f60\u4e0d\u80fd\u63d0\u524d\u77e5\u9053\u4e00\u4e2a\u7c7b\u578b\u91cc\u7684\u6240\u6709\u5c5e\u6027\u7684\u540d\u5b57\uff0c\u4f46\u662f\u4f60\u77e5\u9053\u8fd9\u4e9b\u503c\u7684\u7279\u5f81\u3002<\/p>\n
\u8fd9\u79cd\u60c5\u51b5\uff0c\u4f60\u5c31\u53ef\u4ee5\u7528\u4e00\u4e2a\u7d22\u5f15\u7b7e\u540d (index signature) \u6765\u63cf\u8ff0\u53ef\u80fd\u7684\u503c\u7684\u7c7b\u578b\uff0c\u4e3e\u4e2a\u4f8b\u5b50\uff1a<\/p>\n
<\/p>\n
interface<\/span> StringArray<\/span> {<\/span>\n  [<\/span>index<\/span>: number<\/span>]<\/span>: string<\/span>;<\/span>\n}<\/span>\n \nconst<\/span> myArray<\/span>: StringArray<\/span> =<\/span> getStringArray<\/span>(<\/span>)<\/span>;<\/span>\nconst<\/span> secondItem<\/span> =<\/span> myArray<\/span>[<\/span>1<\/span>]<\/span>;<\/span> \/\/ const secondItem: string<\/span><\/pre>\n<\/div>\n
\u8fd9\u6837\uff0c\u6211\u4eec\u5c31\u6709\u4e86\u4e00\u4e2a\u5177\u6709\u7d22\u5f15\u7b7e\u540d\u7684\u63a5\u53e3 StringArray<\/code>\uff0c\u8fd9\u4e2a\u7d22\u5f15\u7b7e\u540d\u8868\u793a\u5f53\u4e00\u4e2a StringArray<\/code> \u7c7b\u578b\u7684\u503c\u4f7f\u7528 number<\/code> \u7c7b\u578b\u7684\u503c\u8fdb\u884c\u7d22\u5f15\u7684\u65f6\u5019\uff0c\u4f1a\u8fd4\u56de\u4e00\u4e2a string<\/code>\u7c7b\u578b\u7684\u503c\u3002<\/p>\n
\u4e00\u4e2a\u7d22\u5f15\u7b7e\u540d\u7684\u5c5e\u6027\u7c7b\u578b\u5fc5\u987b\u662f string<\/code> \u6216\u8005\u662f number<\/code>\u3002<\/p>\n
\u867d\u7136 TypeScript \u53ef\u4ee5\u540c\u65f6\u652f\u6301 string<\/code> \u548c number<\/code> \u7c7b\u578b\uff0c\u4f46\u6570\u5b57\u7d22\u5f15\u7684\u8fd4\u56de\u7c7b\u578b\u4e00\u5b9a\u8981\u662f\u5b57\u7b26\u7d22\u5f15\u8fd4\u56de\u7c7b\u578b\u7684\u5b50\u7c7b\u578b\u3002\u8fd9\u662f\u56e0\u4e3a\u5f53\u4f7f\u7528\u4e00\u4e2a\u6570\u5b57\u8fdb\u884c\u7d22\u5f15\u7684\u65f6\u5019\uff0cJavaScript \u5b9e\u9645\u4e0a\u628a\u5b83\u8f6c\u6210\u4e86\u4e00\u4e2a\u5b57\u7b26\u4e32\u3002\u8fd9\u5c31\u610f\u5473\u7740\u4f7f\u7528\u6570\u5b57 100 \u8fdb\u884c\u7d22\u5f15\u8ddf\u4f7f\u7528\u5b57\u7b26\u4e32 100 \u7d22\u5f15\uff0c\u662f\u4e00\u6837\u7684\u3002<\/p>\n
<\/p>\n
interface<\/span> Animal<\/span> {<\/span>\n  name<\/span>: string<\/span>;<\/span>\n}<\/span>\n \ninterface<\/span> Dog<\/span> extends<\/span> Animal<\/span> {<\/span>\n  breed<\/span>: string<\/span>;<\/span>\n}<\/span>\n \n\/\/ Error: indexing with a numeric string might get you a completely separate type of Animal!<\/span>\ninterface<\/span> NotOkay<\/span> {<\/span>\n  [<\/span>x<\/span>: number<\/span>]<\/span>: Animal<\/span>;<\/span>\n  \/\/ 'number' index type 'Animal' is not assignable to 'string' index type 'Dog'.<\/span>\n  [<\/span>x<\/span>: string<\/span>]<\/span>: Dog<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u5c3d\u7ba1\u5b57\u7b26\u4e32\u7d22\u5f15\u7528\u6765\u63cf\u8ff0\u5b57\u5178\u6a21\u5f0f\uff08dictionary pattern\uff09\u975e\u5e38\u7684\u6709\u6548\uff0c\u4f46\u4e5f\u4f1a\u5f3a\u5236\u8981\u6c42\u6240\u6709\u7684\u5c5e\u6027\u8981\u5339\u914d\u7d22\u5f15\u7b7e\u540d\u7684\u8fd4\u56de\u7c7b\u578b\u3002\u8fd9\u662f\u56e0\u4e3a\u4e00\u4e2a\u58f0\u660e\u7c7b\u4f3c\u4e8e obj.property<\/code> \u7684\u5b57\u7b26\u4e32\u7d22\u5f15\uff0c\u8ddf obj[\"property\"]<\/code>\u662f\u4e00\u6837\u7684\u3002\u5728\u4e0b\u9762\u7684\u4f8b\u5b50\u4e2d\uff0cname<\/code> \u7684\u7c7b\u578b\u5e76\u4e0d\u5339\u914d\u5b57\u7b26\u4e32\u7d22\u5f15\u7684\u7c7b\u578b\uff0c\u6240\u4ee5\u7c7b\u578b\u68c0\u67e5\u5668\u4f1a\u7ed9\u51fa\u62a5\u9519\uff1a<\/p>\n
<\/p>\n
interface<\/span> NumberDictionary<\/span> {<\/span>\n  [<\/span>index<\/span>: string<\/span>]<\/span>: number<\/span>;<\/span>\n \n  length<\/span>: number<\/span>;<\/span> \/\/ ok<\/span>\n  name<\/span>: string<\/span>;<\/span>\n\t\/\/ Property 'name' of type 'string' is not assignable to 'string' index type 'number'.<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u7136\u800c\uff0c\u5982\u679c\u4e00\u4e2a\u7d22\u5f15\u7b7e\u540d\u662f\u5c5e\u6027\u7c7b\u578b\u7684\u8054\u5408\uff0c\u90a3\u5404\u79cd\u7c7b\u578b\u7684\u5c5e\u6027\u5c31\u53ef\u4ee5\u63a5\u53d7\u4e86\uff1a<\/p>\n
<\/p>\n
interface<\/span> NumberOrStringDictionary<\/span> {<\/span>\n  [<\/span>index<\/span>: string<\/span>]<\/span>: number<\/span> |<\/span> string<\/span>;<\/span>\n  length<\/span>: number<\/span>;<\/span> \/\/ ok, length is a number<\/span>\n  name<\/span>: string<\/span>;<\/span> \/\/ ok, name is a string<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u6700\u540e\uff0c\u4f60\u4e5f\u53ef\u4ee5\u8bbe\u7f6e\u7d22\u5f15\u7b7e\u540d\u4e3a readonly<\/code>\u3002<\/p>\n
<\/p>\n
interface<\/span> ReadonlyStringArray<\/span> {<\/span>\n  readonly<\/span> [<\/span>index<\/span>: number<\/span>]<\/span>: string<\/span>;<\/span>\n}<\/span>\n \nlet<\/span> myArray<\/span>: ReadonlyStringArray<\/span> =<\/span> getReadOnlyStringArray<\/span>(<\/span>)<\/span>;<\/span>\nmyArray<\/span>[<\/span>2<\/span>]<\/span> =<\/span> \"Mallory\"<\/span>;<\/span>\n\/\/ Index signature in type 'ReadonlyStringArray' only permits reading.<\/span><\/pre>\n<\/div>\n
\u56e0\u4e3a\u7d22\u5f15\u7b7e\u540d\u662f readonly<\/code> \uff0c\u6240\u4ee5\u4f60\u65e0\u6cd5\u8bbe\u7f6e myArray[2]<\/code> \u7684\u503c\u3002<\/p>\n
\u5c5e\u6027\u7ee7\u627f\uff08Extending Types\uff09<\/h2>\n
\u6709\u65f6\u6211\u4eec\u9700\u8981\u4e00\u4e2a\u6bd4\u5176\u4ed6\u7c7b\u578b\u66f4\u5177\u4f53\u7684\u7c7b\u578b\u3002\u4e3e\u4e2a\u4f8b\u5b50\uff0c\u5047\u8bbe\u6211\u4eec\u6709\u4e00\u4e2a BasicAddress<\/code> \u7c7b\u578b\u7528\u6765\u63cf\u8ff0\u5728\u7f8e\u56fd\u90ae\u5bc4\u4fe1\u4ef6\u548c\u5305\u88f9\u7684\u6240\u9700\u5b57\u6bb5\u3002<\/p>\n
<\/p>\n
interface<\/span> BasicAddress<\/span> {<\/span>\n  name<\/span>?: string<\/span>;<\/span>\n  street<\/span>: string<\/span>;<\/span>\n  city<\/span>: string<\/span>;<\/span>\n  country<\/span>: string<\/span>;<\/span>\n  postalCode<\/span>: string<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u8fd9\u5728\u4e00\u4e9b\u60c5\u51b5\u4e0b\u5df2\u7ecf\u6ee1\u8db3\u4e86\uff0c\u4f46\u540c\u4e00\u4e2a\u5730\u5740\u7684\u5efa\u7b51\u5f80\u5f80\u8fd8\u6709\u4e0d\u540c\u7684\u5355\u5143\u53f7\uff0c\u6211\u4eec\u53ef\u4ee5\u518d\u5199\u4e00\u4e2a AddressWithUnit<\/code>\uff1a<\/p>\n
<\/p>\n
interface<\/span> AddressWithUnit<\/span> {<\/span>\n  name<\/span>?: string<\/span>;<\/span>\n  unit<\/span>: string<\/span>;<\/span>\n  street<\/span>: string<\/span>;<\/span>\n  city<\/span>: string<\/span>;<\/span>\n  country<\/span>: string<\/span>;<\/span>\n  postalCode<\/span>: string<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u8fd9\u6837\u5199\u56fa\u7136\u53ef\u4ee5\uff0c\u4f46\u4e3a\u4e86\u52a0\u4e00\u4e2a\u5b57\u6bb5\uff0c\u5c31\u662f\u8981\u5b8c\u5168\u7684\u62f7\u8d1d\u4e00\u904d\u3002<\/p>\n
\u6211\u4eec\u53ef\u4ee5\u6539\u6210\u7ee7\u627f BasicAddress<\/code>\u7684\u65b9\u5f0f\u6765\u5b9e\u73b0\uff1a<\/p>\n
<\/p>\n
interface<\/span> BasicAddress<\/span> {<\/span>\n  name<\/span>?: string<\/span>;<\/span>\n  street<\/span>: string<\/span>;<\/span>\n  city<\/span>: string<\/span>;<\/span>\n  country<\/span>: string<\/span>;<\/span>\n  postalCode<\/span>: string<\/span>;<\/span>\n}<\/span>\n \ninterface<\/span> AddressWithUnit<\/span> extends<\/span> BasicAddress<\/span> {<\/span>\n  unit<\/span>: string<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u5bf9\u63a5\u53e3\u4f7f\u7528 extends<\/code>\u5173\u952e\u5b57\u5141\u8bb8\u6211\u4eec\u6709\u6548\u7684\u4ece\u5176\u4ed6\u58f0\u660e\u8fc7\u7684\u7c7b\u578b\u4e2d\u62f7\u8d1d\u6210\u5458\uff0c\u5e76\u4e14\u968f\u610f\u6dfb\u52a0\u65b0\u6210\u5458\u3002<\/p>\n
\u63a5\u53e3\u4e5f\u53ef\u4ee5\u7ee7\u627f\u591a\u4e2a\u7c7b\u578b\uff1a<\/p>\n
<\/p>\n
interface<\/span> Colorful<\/span> {<\/span>\n  color<\/span>: string<\/span>;<\/span>\n}<\/span>\n \ninterface<\/span> Circle<\/span> {<\/span>\n  radius<\/span>: number<\/span>;<\/span>\n}<\/span>\n \ninterface<\/span> ColorfulCircle<\/span> extends<\/span> Colorful<\/span>,<\/span> Circle<\/span> {<\/span>}<\/span>\n \nconst<\/span> cc<\/span>: ColorfulCircle<\/span> =<\/span> {<\/span>\n  color<\/span>: \"red\"<\/span>,<\/span>\n  radius<\/span>: 42<\/span>,<\/span>\n}<\/span>;<\/span><\/pre>\n<\/div>\n
\u4ea4\u53c9\u7c7b\u578b\uff08Intersection Types\uff09<\/h2>\n
TypeScript \u4e5f\u63d0\u4f9b\u4e86\u540d\u4e3a\u4ea4\u53c9\u7c7b\u578b\uff08Intersection types\uff09\u7684\u65b9\u6cd5\uff0c\u7528\u4e8e\u5408\u5e76\u5df2\u7ecf\u5b58\u5728\u7684\u5bf9\u8c61\u7c7b\u578b\u3002<\/p>\n
\u4ea4\u53c9\u7c7b\u578b\u7684\u5b9a\u4e49\u9700\u8981\u7528\u5230 &<\/code> \u64cd\u4f5c\u7b26\uff1a<\/p>\n
<\/p>\n
interface<\/span> Colorful<\/span> {<\/span>\n  color<\/span>: string<\/span>;<\/span>\n}<\/span>\ninterface<\/span> Circle<\/span> {<\/span>\n  radius<\/span>: number<\/span>;<\/span>\n}<\/span>\n \ntype<\/span> ColorfulCircle<\/span> =<\/span> Colorful<\/span> &<\/span> Circle<\/span>;<\/span><\/pre>\n<\/div>\n
\u8fd9\u91cc\uff0c\u6211\u4eec\u8fde\u7ed3 Colorful<\/code> \u548c Circle<\/code> \u4ea7\u751f\u4e86\u4e00\u4e2a\u65b0\u7684\u7c7b\u578b\uff0c\u65b0\u7c7b\u578b\u62e5\u6709 Colorful<\/code> \u548c Circle<\/code> \u7684\u6240\u6709\u6210\u5458\u3002<\/p>\n
<\/p>\n
function<\/span> draw<\/span>(<\/span>circle<\/span>: Colorful<\/span> &<\/span> Circle<\/span>)<\/span> {<\/span>\n  console<\/span>.<\/span>log<\/span>(<\/span>`Color was ${<\/span>circle<\/span>.<\/span>color<\/span>}<\/span><\/span>`<\/span>)<\/span>;<\/span>\n  console<\/span>.<\/span>log<\/span>(<\/span>`Radius was ${<\/span>circle<\/span>.<\/span>radius<\/span>}<\/span><\/span>`<\/span>)<\/span>;<\/span>\n}<\/span>\n \n\/\/ okay<\/span>\ndraw<\/span>(<\/span>{<\/span> color<\/span>: \"blue\"<\/span>,<\/span> radius<\/span>: 42<\/span> }<\/span>)<\/span>;<\/span>\n \n\/\/ oops<\/span>\ndraw<\/span>(<\/span>{<\/span> color<\/span>: \"red\"<\/span>,<\/span> raidus<\/span>: 42<\/span> }<\/span>)<\/span>;<\/span>\n\/\/ Argument of type '{ color: string; raidus: number; }' is not assignable to parameter of type 'Colorful & Circle'.<\/span>\n\/\/ Object literal may only specify known properties, but 'raidus' does not exist in type 'Colorful & Circle'. Did you mean to write 'radius'?<\/span><\/pre>\n<\/div>\n
\u63a5\u53e3\u7ee7\u627f\u4e0e\u4ea4\u53c9\u7c7b\u578b\uff08Interfalces vs Intersections\uff09<\/h2>\n
\u8fd9\u4e24\u79cd\u65b9\u5f0f\u5728\u5408\u5e76\u7c7b\u578b\u4e0a\u770b\u8d77\u6765\u5f88\u76f8\u4f3c\uff0c\u4f46\u5b9e\u9645\u4e0a\u8fd8\u662f\u6709\u5f88\u5927\u7684\u4e0d\u540c\u3002\u6700\u539f\u5219\u6027\u7684\u4e0d\u540c\u5c31\u662f\u5728\u4e8e\u51b2\u7a81\u600e\u4e48\u5904\u7406\uff0c\u8fd9\u4e5f\u662f\u4f60\u51b3\u5b9a\u9009\u62e9\u90a3\u79cd\u65b9\u5f0f\u7684\u4e3b\u8981\u539f\u56e0\u3002<\/p>\n
<\/p>\n
interface<\/span> Colorful<\/span> {<\/span>\n  color<\/span>: string<\/span>;<\/span>\n}<\/span>\n\ninterface<\/span> ColorfulSub<\/span> extends<\/span> Colorful<\/span> {<\/span>\n  color<\/span>: number<\/span>\n}<\/span>\n\n\/\/ Interface 'ColorfulSub' incorrectly extends interface 'Colorful'.<\/span>\n\/\/ Types of property 'color' are incompatible.<\/span>\n\/\/ Type 'number' is not assignable to type 'string'.<\/span><\/pre>\n<\/div>\n
\u4f7f\u7528\u7ee7\u627f\u7684\u65b9\u5f0f\uff0c\u5982\u679c\u91cd\u5199\u7c7b\u578b\u4f1a\u5bfc\u81f4\u7f16\u8bd1\u9519\u8bef\uff0c\u4f46\u4ea4\u53c9\u7c7b\u578b\u4e0d\u4f1a\uff1a<\/p>\n
<\/p>\n
interface<\/span> Colorful<\/span> {<\/span>\n  color<\/span>: string<\/span>;<\/span>\n}<\/span>\n\ntype<\/span> ColorfulSub<\/span> =<\/span> Colorful<\/span> &<\/span> {<\/span>\n  color<\/span>: number<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u867d\u7136\u4e0d\u4f1a\u62a5\u9519\uff0c\u90a3 color<\/code> \u5c5e\u6027\u7684\u7c7b\u578b\u662f\u4ec0\u4e48\u5462\uff0c\u7b54\u6848\u662f never<\/code>\uff0c\u53d6\u5f97\u662f string<\/code> \u548c number<\/code> \u7684\u4ea4\u96c6\u3002<\/p>\n
\u6cdb\u578b\u5bf9\u8c61\u7c7b\u578b\uff08Generic Object Types\uff09<\/h2>\n
\u8ba9\u6211\u4eec\u5199\u8fd9\u6837\u4e00\u4e2a Box<\/code> \u7c7b\u578b\uff0c\u53ef\u4ee5\u5305\u542b\u4efb\u4f55\u503c\uff1a<\/p>\n
<\/p>\n
interface<\/span> Box<\/span> {<\/span>\n  contents<\/span>: any<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u73b0\u5728 content<\/code> \u5c5e\u6027\u7684\u7c7b\u578b\u4e3a any<\/code>\uff0c\u53ef\u4ee5\u7528\uff0c\u4f46\u5bb9\u6613\u5bfc\u81f4\u7ffb\u8f66\u3002<\/p>\n
\u6211\u4eec\u4e5f\u53ef\u4ee5\u4ee3\u66ff\u4f7f\u7528 unknown<\/code>\uff0c\u4f46\u8fd9\u4e5f\u610f\u5473\u7740\uff0c\u5982\u679c\u6211\u4eec\u5df2\u7ecf\u77e5\u9053\u4e86 contents<\/code> \u7684\u7c7b\u578b\uff0c\u6211\u4eec\u9700\u8981\u505a\u4e00\u4e9b\u9884\u9632\u68c0\u67e5\uff0c\u6216\u8005\u7528\u4e00\u4e2a\u5bb9\u6613\u9519\u8bef\u7684\u7c7b\u578b\u65ad\u8a00\u3002<\/p>\n
<\/p>\n
interface<\/span> Box<\/span> {<\/span>\n  contents<\/span>: unknown<\/span>;<\/span>\n}<\/span>\n \nlet<\/span> x<\/span>: Box<\/span> =<\/span> {<\/span>\n  contents<\/span>: \"hello world\"<\/span>,<\/span>\n}<\/span>;<\/span>\n \n\/\/ we could check 'x.contents'<\/span>\nif<\/span> (<\/span>typeof<\/span> x<\/span>.<\/span>contents<\/span> ===<\/span> \"string\"<\/span>)<\/span> {<\/span>\n  console<\/span>.<\/span>log<\/span>(<\/span>x<\/span>.<\/span>contents<\/span>.<\/span>toLowerCase<\/span>(<\/span>)<\/span>)<\/span>;<\/span>\n}<\/span>\n \n\/\/ or we could use a type assertion<\/span>\nconsole<\/span>.<\/span>log<\/span>(<\/span>(<\/span>x<\/span>.<\/span>contents<\/span> as<\/span> string<\/span>)<\/span>.<\/span>toLowerCase<\/span>(<\/span>)<\/span>)<\/span>;<\/span><\/pre>\n<\/div>\n
\u4e00\u4e2a\u66f4\u52a0\u5b89\u5168\u7684\u505a\u6cd5\u662f\u5c06 Box<\/code> \u6839\u636e contents<\/code> \u7684\u7c7b\u578b\u62c6\u5206\u7684\u66f4\u5177\u4f53\u4e00\u4e9b\uff1a<\/p>\n
<\/p>\n
interface<\/span> NumberBox<\/span> {<\/span>\n  contents<\/span>: number<\/span>;<\/span>\n}<\/span>\n \ninterface<\/span> StringBox<\/span> {<\/span>\n  contents<\/span>: string<\/span>;<\/span>\n}<\/span>\n \ninterface<\/span> BooleanBox<\/span> {<\/span>\n  contents<\/span>: boolean<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u4f46\u662f\u8fd9\u4e5f\u610f\u5473\u7740\u6211\u4eec\u4e0d\u5f97\u4e0d\u521b\u5efa\u4e0d\u540c\u7684\u51fd\u6570\u6216\u8005\u51fd\u6570\u91cd\u8f7d\u5904\u7406\u4e0d\u540c\u7684\u7c7b\u578b\uff1a<\/p>\n
<\/p>\n
function<\/span> setContents<\/span>(<\/span>box<\/span>: StringBox<\/span>,<\/span> newContents<\/span>: string<\/span>)<\/span>: void<\/span><\/span>;<\/span>\nfunction<\/span> setContents<\/span>(<\/span>box<\/span>: NumberBox<\/span>,<\/span> newContents<\/span>: number<\/span>)<\/span>: void<\/span><\/span>;<\/span>\nfunction<\/span> setContents<\/span>(<\/span>box<\/span>: BooleanBox<\/span>,<\/span> newContents<\/span>: boolean<\/span>)<\/span>: void<\/span><\/span>;<\/span>\nfunction<\/span> setContents<\/span>(<\/span>box<\/span>: {<\/span> contents<\/span>: any<\/span> }<\/span>,<\/span> newContents<\/span>: any<\/span>)<\/span> {<\/span>\n  box<\/span>.<\/span>contents<\/span> =<\/span> newContents<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u8fd9\u6837\u5199\u5c31\u592a\u7e41\u7410\u4e86\u3002<\/p>\n
\u6240\u4ee5\u6211\u4eec\u53ef\u4ee5\u521b\u5efa\u4e00\u4e2a\u6cdb\u578b Box<\/code> \uff0c\u5b83\u58f0\u660e\u4e86\u4e00\u4e2a\u7c7b\u578b\u53c2\u6570 (type parameter)\uff1a<\/p>\n
<\/p>\n
interface<\/span> Box<\/span><<\/span>Type<\/span>><\/span> {<\/span>\n  contents<\/span>: Type<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u4f60\u53ef\u4ee5\u8fd9\u6837\u7406\u89e3\uff1aBox<\/code> \u7684 Type<\/code> \u5c31\u662f contents<\/code> \u62e5\u6709\u7684\u7c7b\u578b Type<\/code>\u3002<\/p>\n
\u5f53\u6211\u4eec\u5f15\u7528 Box<\/code> \u7684\u65f6\u5019\uff0c\u6211\u4eec\u9700\u8981\u7ed9\u4e88\u4e00\u4e2a\u7c7b\u578b\u5b9e\u53c2\u66ff\u6362\u6389 Type<\/code>\uff1a<\/p>\n
\n
let<\/span> box<\/span>: Box<\/span><<\/span>string<\/span>><\/span>;<\/span><\/pre>\n<\/div>\n
\u628a Box<\/code> \u60f3\u8c61\u6210\u4e00\u4e2a\u5b9e\u9645\u7c7b\u578b\u7684\u6a21\u677f\uff0cType<\/code> \u5c31\u662f\u4e00\u4e2a\u5360\u4f4d\u7b26\uff0c\u53ef\u4ee5\u88ab\u66ff\u4ee3\u4e3a\u5177\u4f53\u7684\u7c7b\u578b\u3002\u5f53 TypeScript \u770b\u5230 Box<string><\/code>\uff0c\u5b83\u5c31\u4f1a\u66ff\u6362\u4e3a Box<Type><\/code> \u7684 Type<\/code> \u4e3a string<\/code> \uff0c\u6700\u540e\u7684\u7ed3\u679c\u5c31\u4f1a\u53d8\u6210 { contents: string }<\/code>\u3002\u6362\u53e5\u8bdd\u8bf4\uff0cBox<string><\/code>\u548c StringBox<\/code> \u662f\u4e00\u6837\u7684\u3002<\/p>\n
<\/p>\n
interface<\/span> Box<\/span><<\/span>Type<\/span>><\/span> {<\/span>\n  contents<\/span>: Type<\/span>;<\/span>\n}<\/span>\ninterface<\/span> StringBox<\/span> {<\/span>\n  contents<\/span>: string<\/span>;<\/span>\n}<\/span>\n \nlet<\/span> boxA<\/span>: Box<\/span><<\/span>string<\/span>><\/span> =<\/span> {<\/span> contents<\/span>: \"hello\"<\/span> }<\/span>;<\/span>\nboxA<\/span>.<\/span>contents<\/span>;<\/span>        \n\/\/ (property) Box<string>.contents: string<\/span>\n \nlet<\/span> boxB<\/span>: StringBox<\/span> =<\/span> {<\/span> contents<\/span>: \"world\"<\/span> }<\/span>;<\/span>\nboxB<\/span>.<\/span>contents<\/span>;<\/span>     \n\/\/ (property) StringBox.contents: string<\/span><\/pre>\n<\/div>\n
\u4e0d\u8fc7\u73b0\u5728\u7684 Box<\/code>  \u662f\u53ef\u91cd\u590d\u4f7f\u7528\u7684\uff0c\u5982\u679c\u6211\u4eec\u9700\u8981\u4e00\u4e2a\u65b0\u7684\u7c7b\u578b\uff0c\u6211\u4eec\u5b8c\u5168\u4e0d\u9700\u8981\u518d\u91cd\u65b0\u58f0\u660e\u4e00\u4e2a\u7c7b\u578b\u3002<\/p>\n
<\/p>\n
interface<\/span> Box<\/span><<\/span>Type<\/span>><\/span> {<\/span>\n  contents<\/span>: Type<\/span>;<\/span>\n}<\/span>\n \ninterface<\/span> Apple<\/span> {<\/span>\n  \/\/ ....<\/span>\n}<\/span>\n \n\/\/ Same as '{ contents: Apple }'.<\/span>\ntype<\/span> AppleBox<\/span> =<\/span> Box<\/span><<\/span>Apple<\/span>><\/span>;<\/span><\/pre>\n<\/div>\n
\u8fd9\u4e5f\u610f\u5473\u7740\u6211\u4eec\u53ef\u4ee5\u5229\u7528\u6cdb\u578b\u51fd\u6570\u907f\u514d\u4f7f\u7528\u51fd\u6570\u91cd\u8f7d\u3002<\/p>\n
<\/p>\n
function<\/span> setContents<\/span><<\/span>Type<\/span>><\/span>(<\/span>box<\/span>: Box<\/span><<\/span>Type<\/span>><\/span>,<\/span> newContents<\/span>: Type<\/span>)<\/span> {<\/span>\n  box<\/span>.<\/span>contents<\/span> =<\/span> newContents<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u7c7b\u578b\u522b\u540d\u4e5f\u662f\u53ef\u4ee5\u4f7f\u7528\u6cdb\u578b\u7684\u3002\u6bd4\u5982\uff1a<\/p>\n
<\/p>\n
interface<\/span> Box<\/span><<\/span>Type<\/span>><\/span> {<\/span>\n  contents<\/span>: Type<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u4f7f\u7528\u522b\u540d\u5bf9\u5e94\u5c31\u662f\uff1a<\/p>\n
<\/p>\n
type<\/span> Box<\/span><<\/span>Type<\/span>><\/span> =<\/span> {<\/span>\n  contents<\/span>: Type<\/span>;<\/span>\n}<\/span>;<\/span><\/pre>\n<\/div>\n
\u7c7b\u578b\u522b\u540d\u4e0d\u540c\u4e8e\u63a5\u53e3\uff0c\u53ef\u4ee5\u63cf\u8ff0\u7684\u4e0d\u6b62\u662f\u5bf9\u8c61\u7c7b\u578b\uff0c\u6240\u4ee5\u6211\u4eec\u4e5f\u53ef\u4ee5\u7528\u7c7b\u578b\u522b\u540d\u5199\u4e00\u4e9b\u5176\u4ed6\u79cd\u7c7b\u7684\u7684\u6cdb\u578b\u5e2e\u52a9\u7c7b\u578b\u3002<\/p>\n
<\/p>\n
type<\/span> OrNull<\/span><<\/span>Type<\/span>><\/span> =<\/span> Type<\/span> |<\/span> null<\/span>;<\/span>\n \ntype<\/span> OneOrMany<\/span><<\/span>Type<\/span>><\/span> =<\/span> Type<\/span> |<\/span> Type<\/span>[<\/span>]<\/span>;<\/span>\n \ntype<\/span> OneOrManyOrNull<\/span><<\/span>Type<\/span>><\/span> =<\/span> OrNull<\/span><<\/span>OneOrMany<\/span><<\/span>Type<\/span>><\/span>><\/span>;<\/span>\n           \ntype<\/span> OneOrManyOrNull<\/span><<\/span>Type<\/span>><\/span> =<\/span> OneOrMany<\/span><<\/span>Type<\/span>><\/span> |<\/span> null<\/span>\n \ntype<\/span> OneOrManyOrNullStrings<\/span> =<\/span> OneOrManyOrNull<\/span><<\/span>string<\/span>><\/span>;<\/span>\n               \ntype<\/span> OneOrManyOrNullStrings<\/span> =<\/span> OneOrMany<\/span><<\/span>string<\/span>><\/span> |<\/span> null<\/span><\/pre>\n<\/div>\n
Array<\/code> \u7c7b\u578b\uff08The Array Type\uff09<\/h3>\n
\u6211\u4eec\u4e4b\u524d\u8bb2\u8fc7 Array<\/code> \u7c7b\u578b\uff0c\u5f53\u6211\u4eec\u8fd9\u6837\u5199\u7c7b\u578b number[]<\/code> \u6216\u8005 string[]<\/code> \u7684\u65f6\u5019\uff0c\u5176\u5b9e\u5b83\u4eec\u53ea\u662f Array<number><\/code> \u548c Array<string><\/code>  \u7684\u7b80\u5199\u5f62\u5f0f\u800c\u5df2\u3002<\/p>\n
<\/p>\n
function<\/span> doSomething<\/span>(<\/span>value<\/span>: Array<\/span><<\/span>string<\/span>><\/span>)<\/span> {<\/span>\n  \/\/ ...<\/span>\n}<\/span>\n \nlet<\/span> myArray<\/span>: string<\/span>[<\/span>]<\/span> =<\/span> [<\/span>\"hello\"<\/span>,<\/span> \"world\"<\/span>]<\/span>;<\/span>\n \n\/\/ either of these work!<\/span>\ndoSomething<\/span>(<\/span>myArray<\/span>)<\/span>;<\/span>\ndoSomething<\/span>(<\/span>new<\/span> Array<\/span>(<\/span>\"hello\"<\/span>,<\/span> \"world\"<\/span>)<\/span>)<\/span>;<\/span><\/pre>\n<\/div>\n
\u7c7b\u4f3c\u4e8e\u4e0a\u9762\u7684 Box<\/code> \u7c7b\u578b\uff0cArray<\/code> \u672c\u8eab\u5c31\u662f\u4e00\u4e2a\u6cdb\u578b\uff1a<\/p>\n
<\/p>\n
interface<\/span> Array<\/span><<\/span>Type<\/span>><\/span> {<\/span>\n  \/**<\/span>\n   * Gets or sets the length of the array.<\/span>\n   *\/<\/span>\n  length<\/span>: number<\/span>;<\/span>\n \n  \/**<\/span>\n   * Removes the last element from an array and returns it.<\/span>\n   *\/<\/span>\n  pop<\/span>(<\/span>)<\/span>: Type<\/span> |<\/span> undefined<\/span>;<\/span>\n \n  \/**<\/span>\n   * Appends new elements to an array, and returns the new length of the array.<\/span>\n   *\/<\/span>\n  push<\/span>(<\/span>...items<\/span>: Type<\/span>[<\/span>]<\/span>)<\/span>: number<\/span>;<\/span>\n \n  \/\/ ...<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u73b0\u4ee3 JavaScript \u4e5f\u63d0\u4f9b\u5176\u4ed6\u662f\u6cdb\u578b\u7684\u6570\u636e\u7ed3\u6784\uff0c\u6bd4\u5982 Map<K, V><\/code> \uff0c Set<T><\/code> \u548c Promise<T><\/code>\u3002\u56e0\u4e3a Map<\/code> \u3001Set<\/code> \u3001Promise<\/code>\u7684\u884c\u4e3a\u8868\u73b0\uff0c\u5b83\u4eec\u53ef\u4ee5\u8ddf\u4efb\u4f55\u7c7b\u578b\u642d\u914d\u4f7f\u7528\u3002<\/p>\n
ReadonlyArray<\/code> \u7c7b\u578b\uff08The ReadonlyArray Type\uff09<\/h3>\n
ReadonlyArray<\/code> \u662f\u4e00\u4e2a\u7279\u6b8a\u7c7b\u578b\uff0c\u5b83\u53ef\u4ee5\u63cf\u8ff0\u6570\u7ec4\u4e0d\u80fd\u88ab\u6539\u53d8\u3002<\/p>\n
<\/p>\n
function<\/span> doStuff<\/span>(<\/span>values<\/span>: ReadonlyArray<\/span><<\/span>string<\/span>><\/span>)<\/span> {<\/span>\n  \/\/ We can read from 'values'...<\/span>\n  const<\/span> copy<\/span> =<\/span> values<\/span>.<\/span>slice<\/span>(<\/span>)<\/span>;<\/span>\n  console<\/span>.<\/span>log<\/span>(<\/span>`The first value is ${<\/span>values<\/span>[<\/span>0<\/span>]<\/span>}<\/span><\/span>`<\/span>)<\/span>;<\/span>\n \n  \/\/ ...but we can't mutate 'values'.<\/span>\n  values<\/span>.<\/span>push<\/span>(<\/span>\"hello!\"<\/span>)<\/span>;<\/span>\n  \/\/ Property 'push' does not exist on type 'readonly string[]'.<\/span>\n}<\/span><\/pre>\n<\/div>\n
ReadonlyArray<\/code> \u4e3b\u8981\u662f\u7528\u6765\u505a\u610f\u56fe\u58f0\u660e\u3002\u5f53\u6211\u4eec\u770b\u5230\u4e00\u4e2a\u51fd\u6570\u8fd4\u56de ReadonlyArray<\/code>\uff0c\u5c31\u662f\u5728\u544a\u8bc9\u6211\u4eec\u4e0d\u80fd\u53bb\u66f4\u6539\u5176\u4e2d\u7684\u5185\u5bb9\uff0c\u5f53\u6211\u4eec\u770b\u5230\u4e00\u4e2a\u51fd\u6570\u652f\u6301\u4f20\u5165 ReadonlyArray<\/code> \uff0c\u8fd9\u662f\u5728\u544a\u8bc9\u6211\u4eec\u6211\u4eec\u53ef\u4ee5\u653e\u5fc3\u7684\u4f20\u5165\u6570\u7ec4\u5230\u51fd\u6570\u4e2d\uff0c\u800c\u4e0d\u7528\u62c5\u5fc3\u4f1a\u6539\u53d8\u6570\u7ec4\u7684\u5185\u5bb9\u3002
\n\u200b
\n\u4e0d\u50cf Array<\/code>\uff0cReadonlyArray<\/code> \u5e76\u4e0d\u662f\u4e00\u4e2a\u6211\u4eec\u53ef\u4ee5\u7528\u7684\u6784\u9020\u5668\u51fd\u6570\u3002<\/p>\n
<\/p>\n
new<\/span> ReadonlyArray<\/span>(<\/span>\"red\"<\/span>,<\/span> \"green\"<\/span>,<\/span> \"blue\"<\/span>)<\/span>;<\/span>\n\/\/ 'ReadonlyArray' only refers to a type, but is being used as a value here.<\/span><\/pre>\n<\/div>\n
\u7136\u800c\uff0c\u6211\u4eec\u53ef\u4ee5\u76f4\u63a5\u628a\u4e00\u4e2a\u5e38\u89c4\u6570\u7ec4\u8d4b\u503c\u7ed9 ReadonlyArray<\/code>\u3002<\/p>\n
\n
const<\/span> roArray<\/span>: ReadonlyArray<\/span><<\/span>string<\/span>><\/span> =<\/span> [<\/span>\"red\"<\/span>,<\/span> \"green\"<\/span>,<\/span> \"blue\"<\/span>]<\/span>;<\/span><\/pre>\n<\/div>\n
TypeScript \u4e5f\u9488\u5bf9 ReadonlyArray<Type><\/code> \u63d0\u4f9b\u4e86\u66f4\u7b80\u77ed\u7684\u5199\u6cd5 readonly Type[]<\/code>\u3002<\/p>\n
<\/p>\n
function<\/span> doStuff<\/span>(<\/span>values<\/span>: readonly<\/span> string<\/span>[<\/span>]<\/span>)<\/span> {<\/span>\n  \/\/ We can read from 'values'...<\/span>\n  const<\/span> copy<\/span> =<\/span> values<\/span>.<\/span>slice<\/span>(<\/span>)<\/span>;<\/span>\n  console<\/span>.<\/span>log<\/span>(<\/span>`The first value is ${<\/span>values<\/span>[<\/span>0<\/span>]<\/span>}<\/span><\/span>`<\/span>)<\/span>;<\/span>\n \n  \/\/ ...but we can't mutate 'values'.<\/span>\n  values<\/span>.<\/span>push<\/span>(<\/span>\"hello!\"<\/span>)<\/span>;<\/span>\n  \/\/ Property 'push' does not exist on type 'readonly string[]'.<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u6700\u540e\u6709\u4e00\u70b9\u8981\u6ce8\u610f\uff0c\u5c31\u662f Arrays<\/code> \u548c ReadonlyArray<\/code> \u5e76\u4e0d\u80fd\u53cc\u5411\u7684\u8d4b\u503c\uff1a<\/p>\n
<\/p>\n
let<\/span> x<\/span>: readonly<\/span> string<\/span>[<\/span>]<\/span> =<\/span> [<\/span>]<\/span>;<\/span>\nlet<\/span> y<\/span>: string<\/span>[<\/span>]<\/span> =<\/span> [<\/span>]<\/span>;<\/span>\n \nx<\/span> =<\/span> y<\/span>;<\/span> \/\/ ok<\/span>\ny<\/span> =<\/span> x<\/span>;<\/span> \/\/ The type 'readonly string[]' is 'readonly' and cannot be assigned to the mutable type 'string[]'.<\/span><\/pre>\n<\/div>\n
\u5143\u7ec4\u7c7b\u578b\uff08Tuple Types\uff09<\/h3>\n
\u5143\u7ec4\u7c7b\u578b\u662f\u53e6\u5916\u4e00\u79cd Array<\/code> \u7c7b\u578b\uff0c\u5f53\u4f60\u660e\u786e\u77e5\u9053\u6570\u7ec4\u5305\u542b\u591a\u5c11\u4e2a\u5143\u7d20\uff0c\u5e76\u4e14\u6bcf\u4e2a\u4f4d\u7f6e\u5143\u7d20\u7684\u7c7b\u578b\u90fd\u660e\u786e\u77e5\u9053\u7684\u65f6\u5019\uff0c\u5c31\u9002\u5408\u4f7f\u7528\u5143\u7ec4\u7c7b\u578b\u3002<\/p>\n
\n
type<\/span> StringNumberPair<\/span> =<\/span> [<\/span>string<\/span>,<\/span> number<\/span>]<\/span>;<\/span><\/pre>\n<\/div>\n
\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0cStringNumberPair<\/code> \u5c31\u662f string<\/code> \u548c number<\/code> \u7684\u5143\u7ec4\u7c7b\u578b\u3002<\/p>\n
\u8ddf ReadonlyArray<\/code> \u4e00\u6837\uff0c\u5b83\u5e76\u4e0d\u4f1a\u5728\u8fd0\u884c\u65f6\u4ea7\u751f\u5f71\u54cd\uff0c\u4f46\u662f\u5bf9 TypeScript \u5f88\u6709\u610f\u4e49\u3002\u56e0\u4e3a\u5bf9\u4e8e\u7c7b\u578b\u7cfb\u7edf\uff0cStringNumberPair<\/code> \u63cf\u8ff0\u4e86\u4e00\u4e2a\u6570\u7ec4\uff0c\u7d22\u5f15 0 \u7684\u503c\u7684\u7c7b\u578b\u662f string<\/code>\uff0c\u7d22\u5f15 1 \u7684\u503c\u7684\u7c7b\u578b\u662f number<\/code>\u3002<\/p>\n
<\/p>\n
function<\/span> doSomething<\/span>(<\/span>pair<\/span>: [<\/span>string<\/span>,<\/span> number<\/span>]<\/span>)<\/span> {<\/span>\n  const<\/span> a<\/span> =<\/span> pair<\/span>[<\/span>0<\/span>]<\/span>;<\/span>\n       \nconst<\/span> a<\/span>: string<\/span>\n  const<\/span> b<\/span> =<\/span> pair<\/span>[<\/span>1<\/span>]<\/span>;<\/span>\n       \nconst<\/span> b<\/span>: number<\/span>\n  \/\/ ...<\/span>\n}<\/span>\n \ndoSomething<\/span>(<\/span>[<\/span>\"hello\"<\/span>,<\/span> 42<\/span>]<\/span>)<\/span>;<\/span><\/pre>\n<\/div>\n
\u5982\u679c\u8981\u83b7\u53d6\u5143\u7d20\u6570\u91cf\u4e4b\u5916\u7684\u5143\u7d20\uff0cTypeScript \u4f1a\u63d0\u793a\u9519\u8bef\uff1a<\/p>\n
<\/p>\n
function<\/span> doSomething<\/span>(<\/span>pair<\/span>: [<\/span>string<\/span>,<\/span> number<\/span>]<\/span>)<\/span> {<\/span>\n  \/\/ ...<\/span>\n \n  const<\/span> c<\/span> =<\/span> pair<\/span>[<\/span>2<\/span>]<\/span>;<\/span>\n  \/\/ Tuple type '[string, number]' of length '2' has no element at index '2'.<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u6211\u4eec\u4e5f\u53ef\u4ee5\u4f7f\u7528 JavaScript \u7684\u6570\u7ec4\u89e3\u6784\u8bed\u6cd5\u89e3\u6784\u5143\u7ec4\uff1a<\/p>\n
<\/p>\n
function<\/span> doSomething<\/span>(<\/span>stringHash<\/span>: [<\/span>string<\/span>,<\/span> number<\/span>]<\/span>)<\/span> {<\/span>\n  const<\/span> [<\/span>inputString<\/span>,<\/span> hash<\/span>]<\/span> =<\/span> stringHash<\/span>;<\/span>\n  console<\/span>.<\/span>log<\/span>(<\/span>inputString<\/span>)<\/span>;<\/span> \/\/ const inputString: string<\/span>\n  console<\/span>.<\/span>log<\/span>(<\/span>hash<\/span>)<\/span>;<\/span> \/\/ const hash: number<\/span>\n}<\/span><\/pre>\n<\/div>\n
\n
\u5143\u7ec4\u7c7b\u578b\u5728\u91cd\u5ea6\u4f9d\u8d56\u7ea6\u5b9a\u7684 API \u4e2d\u5f88\u6709\u7528\uff0c\u56e0\u4e3a\u5b83\u4f1a\u8ba9\u6bcf\u4e2a\u5143\u7d20\u7684\u610f\u4e49\u90fd\u5f88\u660e\u663e\u3002\u5f53\u6211\u4eec\u89e3\u6784\u7684\u65f6\u5019\uff0c\u5143\u7ec4\u7ed9\u4e86\u6211\u4eec\u547d\u540d\u53d8\u91cf\u7684\u81ea\u7531\u5ea6\u3002\u5728\u4e0a\u9762\u7684\u4f8b\u5b50\u4e2d\uff0c\u6211\u4eec\u53ef\u4ee5\u547d\u540d\u5143\u7d20 0<\/code> \u548c 1<\/code> \u4e3a\u6211\u4eec\u60f3\u8981\u7684\u540d\u5b57\u3002<\/p>\n<\/blockquote>\n
\n
\u7136\u800c\uff0c\u4e5f\u4e0d\u662f\u6bcf\u4e2a\u7528\u6237\u90fd\u8fd9\u6837\u8ba4\u4e3a\uff0c\u6240\u4ee5\u6709\u7684\u65f6\u5019\uff0c\u4f7f\u7528\u4e00\u4e2a\u5e26\u6709\u63cf\u8ff0\u5c5e\u6027\u540d\u5b57\u7684\u5bf9\u8c61\u4e5f\u8bb8\u662f\u4e2a\u66f4\u597d\u7684\u65b9\u5f0f\u3002<\/p>\n<\/blockquote>\n
\u9664\u4e86\u957f\u5ea6\u68c0\u67e5\uff0c\u7b80\u5355\u7684\u5143\u7ec4\u7c7b\u578b\u8ddf\u58f0\u660e\u4e86 length<\/code> \u5c5e\u6027\u548c\u5177\u4f53\u7684\u7d22\u5f15\u5c5e\u6027\u7684 Array<\/code> \u662f\u4e00\u6837\u7684\u3002<\/p>\n
<\/p>\n
interface<\/span> StringNumberPair<\/span> {<\/span>\n  \/\/ specialized properties<\/span>\n  length<\/span>: 2<\/span>;<\/span>\n  0<\/span>: string<\/span>;<\/span>\n  1<\/span>: number<\/span>;<\/span>\n \n  \/\/ Other 'Array<string | number>' members...<\/span>\n  slice<\/span>(<\/span>start<\/span>?: number<\/span>,<\/span> end<\/span>?: number<\/span>)<\/span>: Array<\/span><<\/span>string<\/span> |<\/span> number<\/span>><\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u5728\u5143\u7ec4\u7c7b\u578b\u4e2d\uff0c\u4f60\u4e5f\u53ef\u4ee5\u5199\u4e00\u4e2a\u53ef\u9009\u5c5e\u6027\uff0c\u4f46\u53ef\u9009\u5143\u7d20\u5fc5\u987b\u5728\u6700\u540e\u9762\uff0c\u800c\u4e14\u4e5f\u4f1a\u5f71\u54cd\u7c7b\u578b\u7684 length<\/code> \u3002<\/p>\n
<\/p>\n
type<\/span> Either2dOr3d<\/span> =<\/span> [<\/span>number<\/span>,<\/span> number<\/span>,<\/span> number<\/span>?]<\/span>;<\/span>\n \nfunction<\/span> setCoordinate<\/span>(<\/span>coord<\/span>: Either2dOr3d<\/span>)<\/span> {<\/span>\n  const<\/span> [<\/span>x<\/span>,<\/span> y<\/span>,<\/span> z<\/span>]<\/span> =<\/span> coord<\/span>;<\/span>            \n   \/\/  const z: number | undefined<\/span>\n \n  console<\/span>.<\/span>log<\/span>(<\/span>`Provided coordinates had ${<\/span>coord<\/span>.<\/span>length<\/span>}<\/span><\/span> dimensions`<\/span>)<\/span>;<\/span>\n  \/\/ (property) length: 2 | 3<\/span>\n}<\/span><\/pre>\n<\/div>\n
Tuples \u4e5f\u53ef\u4ee5\u4f7f\u7528\u5269\u4f59\u5143\u7d20\u8bed\u6cd5\uff0c\u4f46\u5fc5\u987b\u662f array\/tuple \u7c7b\u578b\uff1a<\/p>\n
<\/p>\n
type<\/span> StringNumberBooleans<\/span> =<\/span> [<\/span>string<\/span>,<\/span> number<\/span>,<\/span> ...boolean<\/span>[<\/span>]<\/span>]<\/span>;<\/span>\ntype<\/span> StringBooleansNumber<\/span> =<\/span> [<\/span>string<\/span>,<\/span> ...boolean<\/span>[<\/span>]<\/span>,<\/span> number<\/span>]<\/span>;<\/span>\ntype<\/span> BooleansStringNumber<\/span> =<\/span> [<\/span>...boolean<\/span>[<\/span>]<\/span>,<\/span> string<\/span>,<\/span> number<\/span>]<\/span>;<\/span><\/pre>\n<\/div>\n
\u6709\u5269\u4f59\u5143\u7d20\u7684\u5143\u7ec4\u5e76\u4e0d\u4f1a\u8bbe\u7f6e length<\/code>\uff0c\u56e0\u4e3a\u5b83\u53ea\u77e5\u9053\u5728\u4e0d\u540c\u4f4d\u7f6e\u4e0a\u7684\u5df2\u77e5\u5143\u7d20\u4fe1\u606f\uff1a<\/p>\n
<\/p>\n
const<\/span> a<\/span>: StringNumberBooleans<\/span> =<\/span> [<\/span>\"hello\"<\/span>,<\/span> 1<\/span>]<\/span>;<\/span>\nconst<\/span> b<\/span>: StringNumberBooleans<\/span> =<\/span> [<\/span>\"beautiful\"<\/span>,<\/span> 2<\/span>,<\/span> true<\/span>]<\/span>;<\/span>\nconst<\/span> c<\/span>: StringNumberBooleans<\/span> =<\/span> [<\/span>\"world\"<\/span>,<\/span> 3<\/span>,<\/span> true<\/span>,<\/span> false<\/span>,<\/span> true<\/span>,<\/span> false<\/span>,<\/span> true<\/span>]<\/span>;<\/span>\n\nconsole<\/span>.<\/span>log<\/span>(<\/span>a<\/span>.<\/span>length<\/span>)<\/span>;<\/span> \/\/ (property) length: number<\/span>\n\ntype<\/span> StringNumberPair<\/span> =<\/span> [<\/span>string<\/span>,<\/span> number<\/span>]<\/span>;<\/span>\nconst<\/span> d<\/span>: StringNumberPair<\/span> =<\/span> [<\/span>'1'<\/span>,<\/span> 1<\/span>]<\/span>;<\/span>\nconsole<\/span>.<\/span>log<\/span>(<\/span>d<\/span>.<\/span>length<\/span>)<\/span>;<\/span> \/\/ (property) length: 2<\/span><\/pre>\n<\/div>\n
\u53ef\u9009\u5143\u7d20\u548c\u5269\u4f59\u5143\u7d20\u7684\u5b58\u5728\uff0c\u4f7f\u5f97 TypeScript \u53ef\u4ee5\u5728\u53c2\u6570\u5217\u8868\u91cc\u4f7f\u7528\u5143\u7ec4\uff0c\u5c31\u50cf\u8fd9\u6837\uff1a<\/p>\n
<\/p>\n
function<\/span> readButtonInput<\/span>(<\/span>...args<\/span>: [<\/span>string<\/span>,<\/span> number<\/span>,<\/span> ...boolean<\/span>[<\/span>]<\/span>]<\/span>)<\/span> {<\/span>\n  const<\/span> [<\/span>name<\/span>,<\/span> version<\/span>,<\/span> ...input<\/span>]<\/span> =<\/span> args<\/span>;<\/span>\n  \/\/ ...<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u57fa\u672c\u7b49\u540c\u4e8e\uff1a<\/p>\n
<\/p>\n
function<\/span> readButtonInput<\/span>(<\/span>name<\/span>: string<\/span>,<\/span> version<\/span>: number<\/span>,<\/span> ...input<\/span>: boolean<\/span>[<\/span>]<\/span>)<\/span> {<\/span>\n  \/\/ ...<\/span>\n}<\/span><\/pre>\n<\/div>\n
readonly<\/code> \u5143\u7ec4\u7c7b\u578b\uff08readonly Tuple Types\uff09<\/h3>\n
\u5143\u7ec4\u7c7b\u578b\u4e5f\u662f\u53ef\u4ee5\u8bbe\u7f6e readonly<\/code> \u7684\uff1a<\/p>\n
<\/p>\n
function<\/span> doSomething<\/span>(<\/span>pair<\/span>: readonly<\/span> [<\/span>string<\/span>,<\/span> number<\/span>]<\/span>)<\/span> {<\/span>\n  \/\/ ...<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u8fd9\u6837 TypeScript \u5c31\u4e0d\u4f1a\u5141\u8bb8\u5199\u5165readonly<\/code> \u5143\u7ec4\u7684\u4efb\u4f55\u5c5e\u6027\uff1a<\/p>\n
<\/p>\n
function<\/span> doSomething<\/span>(<\/span>pair<\/span>: readonly<\/span> [<\/span>string<\/span>,<\/span> number<\/span>]<\/span>)<\/span> {<\/span>\n  pair<\/span>[<\/span>0<\/span>]<\/span> =<\/span> \"hello!\"<\/span>;<\/span>\n  \/\/ Cannot assign to '0' because it is a read-only property.<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u5728\u5927\u90e8\u5206\u7684\u4ee3\u7801\u4e2d\uff0c\u5143\u7ec4\u53ea\u662f\u88ab\u521b\u5efa\uff0c\u4f7f\u7528\u5b8c\u540e\u4e5f\u4e0d\u4f1a\u88ab\u4fee\u6539\uff0c\u6240\u4ee5\u5c3d\u53ef\u80fd\u7684\u5c06\u5143\u7ec4\u8bbe\u7f6e\u4e3a readonly<\/code> \u662f\u4e00\u4e2a\u597d\u4e60\u60ef\u3002<\/p>\n
\u5982\u679c\u6211\u4eec\u7ed9\u4e00\u4e2a\u6570\u7ec4\u5b57\u9762\u91cf const<\/code> \u65ad\u8a00\uff0c\u4e5f\u4f1a\u88ab\u63a8\u65ad\u4e3a readonly<\/code> \u5143\u7ec4\u7c7b\u578b\u3002<\/p>\n
<\/p>\n
let<\/span> point<\/span> =<\/span> [<\/span>3<\/span>,<\/span> 4<\/span>]<\/span> as<\/span> const<\/span>;<\/span>\n \nfunction<\/span> distanceFromOrigin<\/span>(<\/span>[<\/span>x<\/span>,<\/span> y<\/span>]<\/span>: [<\/span>number<\/span>,<\/span> number<\/span>]<\/span>)<\/span> {<\/span>\n  return<\/span> Math<\/span>.<\/span>sqrt<\/span>(<\/span>x<\/span> **<\/span> 2<\/span> +<\/span> y<\/span> **<\/span> 2<\/span>)<\/span>;<\/span>\n}<\/span>\n \ndistanceFromOrigin<\/span>(<\/span>point<\/span>)<\/span>;<\/span>\n\n\/\/ Argument of type 'readonly [3, 4]' is not assignable to parameter of type '[number, number]'.<\/span>\n\/\/ The type 'readonly [3, 4]' is 'readonly' and cannot be assigned to the mutable type '[number, number]'.<\/span><\/pre>\n<\/div>\n
\u5c3d\u7ba1 distanceFromOrigin<\/code> \u5e76\u6ca1\u6709\u66f4\u6539\u4f20\u5165\u7684\u5143\u7d20\uff0c\u4f46\u51fd\u6570\u5e0c\u671b\u4f20\u5165\u4e00\u4e2a\u53ef\u53d8\u5143\u7ec4\u3002\u56e0\u4e3a point<\/code> \u7684\u7c7b\u578b\u88ab\u63a8\u65ad\u4e3a readonly [3, 4]<\/code>\uff0c\u5b83\u8ddf [number number]<\/code> \u5e76\u4e0d\u517c\u5bb9\uff0c\u6240\u4ee5 TypeScript \u7ed9\u4e86\u4e00\u4e2a\u62a5\u9519\u3002<\/p>\n
TypeScript \u7cfb\u5217<\/h2>\n
TypeScript \u7cfb\u5217\u6587\u7ae0\u7531\u5b98\u65b9\u6587\u6863\u7ffb\u8bd1\u3001\u91cd\u96be\u70b9\u89e3\u6790\u3001\u5b9e\u6218\u6280\u5de7\u4e09\u4e2a\u90e8\u5206\u7ec4\u6210\uff0c\u6db5\u76d6\u5165\u95e8\u3001\u8fdb\u9636\u3001\u5b9e\u6218\uff0c\u65e8\u5728\u4e3a\u4f60\u63d0\u4f9b\u4e00\u4e2a\u7cfb\u7edf\u5b66\u4e60 TS \u7684\u6559\u7a0b\uff0c\u5168\u7cfb\u5217\u9884\u8ba1 40 \u7bc7\u5de6\u53f3\u3002\u70b9\u6b64\u6d4f\u89c8\u5168\u7cfb\u5217\u6587\u7ae0\uff0c\u5e76\u5efa\u8bae\u987a\u4fbf\u6536\u85cf\u7ad9\u70b9\u3002<\/a><\/p>\n
\u5fae\u4fe1\uff1a\u300cmqyqingfeng\u300d\uff0c\u52a0\u6211\u8fdb\u51b4\u7fbd\u552f\u4e00\u7684\u8bfb\u8005\u7fa4\u3002<\/p>\n<\/td>\n
\u6587\u7ae0\u8f6c\u8f7d\u81eahttps:\/\/github.com\/mqyqingfeng\/Blog\/issues\/221<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
\u524d\u8a00 TypeScript \u7684\u5b98\u65b9\u6587\u6863\u65e9\u5df2\u66f4\u65b0\uff0c\u4f46\u6211\u80fd\u627e\u5230\u7684\u4e2d\u6587\u6587\u6863\u90fd\u8fd8\u505c\u7559\u5728\u6bd4\u8f83\u8001\u7684\u7248\u672c\u3002\u6240\u4ee5\u5bf9\u5176\u4e2d\u65b0\u589e\u4ee5\u53ca\u4fee\u8ba2\u8f83\u591a\u7684\u4e00\u4e9b\u7ae0\u8282\u8fdb\u884c\u4e86\u7ffb\u8bd1\u6574\u7406\u3002 \u672c\u7bc7\u6574\u7406\u81ea T…<\/p>\n
 Read More  Read More<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1412","post","type-post","status-publish","format-standard","hentry","category-learn"],"_links":{"self":[{"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/posts\/1412"}],"collection":[{"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.lccc.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1412"}],"version-history":[{"count":1,"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/posts\/1412\/revisions"}],"predecessor-version":[{"id":2402,"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/posts\/1412\/revisions\/2402"}],"wp:attachment":[{"href":"https:\/\/www.lccc.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1412"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lccc.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1412"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lccc.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1412"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}