{"id":1379,"date":"2024-06-02T22:29:01","date_gmt":"2024-06-02T22:29:01","guid":{"rendered":""},"modified":"2024-06-05T03:09:46","modified_gmt":"2024-06-04T19:09:46","slug":"javascript%e4%b8%93%e9%a2%98%e4%b9%8b%e7%b1%bb%e5%9e%8b%e5%88%a4%e6%96%ad%e4%b8%8b","status":"publish","type":"post","link":"https:\/\/www.lccc.top\/?p=1379","title":{"rendered":"JavaScript\u4e13\u9898\u4e4b\u7c7b\u578b\u5224\u65ad(\u4e0b)"},"content":{"rendered":"\n

\u524d\u8a00<\/h2>\n

\u5728\u4e0a\u7bc7\u300aJavaScript\u4e13\u9898\u4e4b\u7c7b\u578b\u5224\u65ad(\u4e0a)\u300b<\/a>\u4e2d\uff0c\u6211\u4eec\u6284\u88ad jQuery \u5199\u4e86\u4e00\u4e2a type \u51fd\u6570\uff0c\u53ef\u4ee5\u68c0\u6d4b\u51fa\u5e38\u89c1\u7684\u6570\u636e\u7c7b\u578b\uff0c\u7136\u800c\u5728\u5f00\u53d1\u4e2d\u8fd8\u6709\u66f4\u52a0\u590d\u6742\u7684\u5224\u65ad\uff0c\u6bd4\u5982 plainObject\u3001\u7a7a\u5bf9\u8c61\u3001Window \u5bf9\u8c61\u7b49\uff0c\u8fd9\u4e00\u7bc7\u5c31\u8ba9\u6211\u4eec\u63a5\u7740\u6284\u88ad jQuery \u53bb\u770b\u4e00\u4e0b\u8fd9\u4e9b\u7c7b\u578b\u7684\u5224\u65ad\u3002<\/p>\n

plainObject<\/h2>\n

plainObject \u6765\u81ea\u4e8e jQuery\uff0c\u53ef\u4ee5\u7ffb\u8bd1\u6210\u7eaf\u7cb9\u7684\u5bf9\u8c61\uff0c\u6240\u8c13”\u7eaf\u7cb9\u7684\u5bf9\u8c61”\uff0c\u5c31\u662f\u8be5\u5bf9\u8c61\u662f\u901a\u8fc7 “{}” \u6216 “new Object” \u521b\u5efa\u7684\uff0c\u8be5\u5bf9\u8c61\u542b\u6709\u96f6\u4e2a\u6216\u8005\u591a\u4e2a\u952e\u503c\u5bf9\u3002<\/p>\n

\u4e4b\u6240\u4ee5\u8981\u5224\u65ad\u662f\u4e0d\u662f plainObject\uff0c\u662f\u4e3a\u4e86\u8ddf\u5176\u4ed6\u7684 JavaScript\u5bf9\u8c61\u5982 null\uff0c\u6570\u7ec4\uff0c\u5bbf\u4e3b\u5bf9\u8c61\uff08documents\uff09\u7b49\u4f5c\u533a\u5206\uff0c\u56e0\u4e3a\u8fd9\u4e9b\u7528 typeof \u90fd\u4f1a\u8fd4\u56deobject\u3002<\/p>\n

jQuery\u63d0\u4f9b\u4e86 isPlainObject \u65b9\u6cd5\u8fdb\u884c\u5224\u65ad\uff0c\u5148\u8ba9\u6211\u4eec\u770b\u770b\u4f7f\u7528\u7684\u6548\u679c\uff1a<\/p>\n

<\/p>\n
function<\/span> Person<\/span>(<\/span>name<\/span>)<\/span> {<\/span>\n    this<\/span>.<\/span>name<\/span> =<\/span> name<\/span>;<\/span>\n}<\/span>\n\nconsole<\/span>.<\/span>log<\/span>(<\/span>$<\/span>.<\/span>isPlainObject<\/span>(<\/span>{<\/span>}<\/span>)<\/span>)<\/span> \/\/ true<\/span>\n\nconsole<\/span>.<\/span>log<\/span>(<\/span>$<\/span>.<\/span>isPlainObject<\/span>(<\/span>new<\/span> Object<\/span>)<\/span>)<\/span> \/\/ true<\/span>\n\nconsole<\/span>.<\/span>log<\/span>(<\/span>$<\/span>.<\/span>isPlainObject<\/span>(<\/span>Object<\/span>.<\/span>create<\/span>(<\/span>null<\/span>)<\/span>)<\/span>)<\/span>;<\/span> \/\/ true<\/span>\n\nconsole<\/span>.<\/span>log<\/span>(<\/span>$<\/span>.<\/span>isPlainObject<\/span>(<\/span>Object<\/span>.<\/span>assign<\/span>(<\/span>{<\/span>a<\/span>: 1<\/span>}<\/span>,<\/span> {<\/span>b<\/span>: 2<\/span>}<\/span>)<\/span>)<\/span>)<\/span>;<\/span> \/\/ true<\/span>\n\nconsole<\/span>.<\/span>log<\/span>(<\/span>$<\/span>.<\/span>isPlainObject<\/span>(<\/span>new<\/span> Person<\/span>(<\/span>'yayu'<\/span>)<\/span>)<\/span>)<\/span>;<\/span> \/\/ false<\/span>\n\nconsole<\/span>.<\/span>log<\/span>(<\/span>$<\/span>.<\/span>isPlainObject<\/span>(<\/span>Object<\/span>.<\/span>create<\/span>(<\/span>{<\/span>}<\/span>)<\/span>)<\/span>)<\/span>;<\/span> \/\/ false<\/span><\/pre>\n<\/div>\n
\u7531\u6b64\u6211\u4eec\u53ef\u4ee5\u770b\u5230\uff0c\u9664\u4e86 {} \u548c new Object \u521b\u5efa\u7684\u4e4b\u5916\uff0cjQuery \u8ba4\u4e3a\u4e00\u4e2a\u6ca1\u6709\u539f\u578b\u7684\u5bf9\u8c61\u4e5f\u662f\u4e00\u4e2a\u7eaf\u7cb9\u7684\u5bf9\u8c61\u3002<\/p>\n
\u5b9e\u9645\u4e0a\u968f\u7740 jQuery \u7248\u672c\u7684\u63d0\u5347\uff0cisPlainObject \u7684\u5b9e\u73b0\u4e5f\u5728\u53d8\u5316\uff0c\u6211\u4eec\u4eca\u5929\u8bb2\u7684\u662f 3.0 \u7248\u672c\u4e0b\u7684 isPlainObject\uff0c\u6211\u4eec\u76f4\u63a5\u770b\u6e90\u7801\uff1a<\/p>\n
<\/p>\n
\/\/ \u4e0a\u8282\u4e2d\u5199 type \u51fd\u6570\u65f6\uff0c\u7528\u6765\u5b58\u653e toString \u6620\u5c04\u7ed3\u679c\u7684\u5bf9\u8c61<\/span>\nvar<\/span> class2type<\/span> =<\/span> {<\/span>}<\/span>;<\/span>\n\n\/\/ \u76f8\u5f53\u4e8e Object.prototype.toString<\/span>\nvar<\/span> toString<\/span> =<\/span> class2type<\/span>.<\/span>toString<\/span>;<\/span>\n\n\/\/ \u76f8\u5f53\u4e8e Object.prototype.hasOwnProperty<\/span>\nvar<\/span> hasOwn<\/span> =<\/span> class2type<\/span>.<\/span>hasOwnProperty<\/span>;<\/span>\n\nfunction<\/span> isPlainObject<\/span>(<\/span>obj<\/span>)<\/span> {<\/span>\n    var<\/span> proto<\/span>,<\/span> Ctor<\/span>;<\/span>\n\n    \/\/ \u6392\u9664\u6389\u660e\u663e\u4e0d\u662fobj\u7684\u4ee5\u53ca\u4e00\u4e9b\u5bbf\u4e3b\u5bf9\u8c61\u5982Window<\/span>\n    if<\/span> (<\/span>!<\/span>obj<\/span> ||<\/span> toString<\/span>.<\/span>call<\/span>(<\/span>obj<\/span>)<\/span> !==<\/span> \"[object Object]\"<\/span>)<\/span> {<\/span>\n        return<\/span> false<\/span>;<\/span>\n    }<\/span>\n\n    \/**<\/span>\n     * getPrototypeOf es5 \u65b9\u6cd5\uff0c\u83b7\u53d6 obj \u7684\u539f\u578b<\/span>\n     * \u4ee5 new Object \u521b\u5efa\u7684\u5bf9\u8c61\u4e3a\u4f8b\u7684\u8bdd<\/span>\n     * obj.__proto__ === Object.prototype<\/span>\n     *\/<\/span>\n    proto<\/span> =<\/span> Object<\/span>.<\/span>getPrototypeOf<\/span>(<\/span>obj<\/span>)<\/span>;<\/span>\n\n    \/\/ \u6ca1\u6709\u539f\u578b\u7684\u5bf9\u8c61\u662f\u7eaf\u7cb9\u7684\uff0cObject.create(null) \u5c31\u5728\u8fd9\u91cc\u8fd4\u56de true<\/span>\n    if<\/span> (<\/span>!<\/span>proto<\/span>)<\/span> {<\/span>\n        return<\/span> true<\/span>;<\/span>\n    }<\/span>\n\n    \/**<\/span>\n     * \u4ee5\u4e0b\u5224\u65ad\u901a\u8fc7 new Object \u65b9\u5f0f\u521b\u5efa\u7684\u5bf9\u8c61<\/span>\n     * \u5224\u65ad proto \u662f\u5426\u6709 constructor \u5c5e\u6027\uff0c\u5982\u679c\u6709\u5c31\u8ba9 Ctor \u7684\u503c\u4e3a proto.constructor<\/span>\n     * \u5982\u679c\u662f Object \u51fd\u6570\u521b\u5efa\u7684\u5bf9\u8c61\uff0cCtor \u5728\u8fd9\u91cc\u5c31\u7b49\u4e8e Object \u6784\u9020\u51fd\u6570<\/span>\n     *\/<\/span>\n    Ctor<\/span> =<\/span> hasOwn<\/span>.<\/span>call<\/span>(<\/span>proto<\/span>,<\/span> \"constructor\"<\/span>)<\/span> &&<\/span> proto<\/span>.<\/span>constructor<\/span>;<\/span>\n\n    \/\/ \u5728\u8fd9\u91cc\u5224\u65ad Ctor \u6784\u9020\u51fd\u6570\u662f\u4e0d\u662f Object \u6784\u9020\u51fd\u6570\uff0c\u7528\u4e8e\u533a\u5206\u81ea\u5b9a\u4e49\u6784\u9020\u51fd\u6570\u548c Object \u6784\u9020\u51fd\u6570<\/span>\n    return<\/span> typeof<\/span> Ctor<\/span> ===<\/span> \"function\"<\/span> &&<\/span> hasOwn<\/span>.<\/span>toString<\/span>.<\/span>call<\/span>(<\/span>Ctor<\/span>)<\/span> ===<\/span> hasOwn<\/span>.<\/span>toString<\/span>.<\/span>call<\/span>(<\/span>Object<\/span>)<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u6ce8\u610f\uff1a\u6211\u4eec\u5224\u65ad Ctor \u6784\u9020\u51fd\u6570\u662f\u4e0d\u662f Object \u6784\u9020\u51fd\u6570\uff0c\u7528\u7684\u662f hasOwn.toString.call(Ctor)\uff0c\u8fd9\u4e2a\u65b9\u6cd5\u53ef\u4e0d\u662f Object.prototype.toString\uff0c\u4e0d\u4fe1\u6211\u4eec\u5728\u51fd\u6570\u91cc\u52a0\u4e0a\u4e0b\u9762\u8fd9\u4e24\u53e5\u8bdd\uff1a<\/p>\n
<\/p>\n
console<\/span>.<\/span>log<\/span>(<\/span>hasOwn<\/span>.<\/span>toString<\/span>.<\/span>call<\/span>(<\/span>Ctor<\/span>)<\/span>)<\/span>;<\/span> \/\/ function Object() { [native code] }<\/span>\nconsole<\/span>.<\/span>log<\/span>(<\/span>Object<\/span>.<\/span>prototype<\/span>.<\/span>toString<\/span>.<\/span>call<\/span>(<\/span>Ctor<\/span>)<\/span>)<\/span>;<\/span> \/\/ [object Function]<\/span><\/pre>\n<\/div>\n
\u53d1\u73b0\u8fd4\u56de\u7684\u503c\u5e76\u4e0d\u4e00\u6837\uff0c\u8fd9\u662f\u56e0\u4e3a hasOwn.toString \u8c03\u7528\u7684\u5176\u5b9e\u662f Function.prototype.toString\uff0c\u6bd5\u7adf hasOwnProperty \u53ef\u662f\u4e00\u4e2a\u51fd\u6570\uff01<\/p>\n
\u800c\u4e14 Function \u5bf9\u8c61\u8986\u76d6\u4e86\u4ece Object \u7ee7\u627f\u6765\u7684 Object.prototype.toString \u65b9\u6cd5\u3002\u51fd\u6570\u7684 toString \u65b9\u6cd5\u4f1a\u8fd4\u56de\u4e00\u4e2a\u8868\u793a\u51fd\u6570\u6e90\u4ee3\u7801\u7684\u5b57\u7b26\u4e32\u3002\u5177\u4f53\u6765\u8bf4\uff0c\u5305\u62ec function\u5173\u952e\u5b57\uff0c\u5f62\u53c2\u5217\u8868\uff0c\u5927\u62ec\u53f7\uff0c\u4ee5\u53ca\u51fd\u6570\u4f53\u4e2d\u7684\u5185\u5bb9\u3002<\/p>\n
EmptyObject<\/h2>\n
jQuery\u63d0\u4f9b\u4e86 isEmptyObject \u65b9\u6cd5\u6765\u5224\u65ad\u662f\u5426\u662f\u7a7a\u5bf9\u8c61\uff0c\u4ee3\u7801\u7b80\u5355\uff0c\u6211\u4eec\u76f4\u63a5\u770b\u6e90\u7801\uff1a<\/p>\n
<\/p>\n
function<\/span> isEmptyObject<\/span>(<\/span> obj<\/span> )<\/span> {<\/span>\n\n        var<\/span> name<\/span>;<\/span>\n\n        for<\/span> (<\/span> name<\/span> in<\/span> obj<\/span> )<\/span> {<\/span>\n            return<\/span> false<\/span>;<\/span>\n        }<\/span>\n\n        return<\/span> true<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u5176\u5b9e\u6240\u8c13\u7684 isEmptyObject \u5c31\u662f\u5224\u65ad\u662f\u5426\u6709\u5c5e\u6027\uff0cfor \u5faa\u73af\u4e00\u65e6\u6267\u884c\uff0c\u5c31\u8bf4\u660e\u6709\u5c5e\u6027\uff0c\u6709\u5c5e\u6027\u5c31\u4f1a\u8fd4\u56de false\u3002<\/p>\n
\u4f46\u662f\u6839\u636e\u8fd9\u4e2a\u6e90\u7801\u6211\u4eec\u53ef\u4ee5\u770b\u51faisEmptyObject\u5b9e\u9645\u4e0a\u5224\u65ad\u7684\u5e76\u4e0d\u4ec5\u4ec5\u662f\u7a7a\u5bf9\u8c61\u3002<\/p>\n
\u4e3e\u4e2a\u6817\u5b50\uff1a<\/p>\n
<\/p>\n
console<\/span>.<\/span>log<\/span>(<\/span>isEmptyObject<\/span>(<\/span>{<\/span>}<\/span>)<\/span>)<\/span>;<\/span> \/\/ true<\/span>\nconsole<\/span>.<\/span>log<\/span>(<\/span>isEmptyObject<\/span>(<\/span>[<\/span>]<\/span>)<\/span>)<\/span>;<\/span> \/\/ true<\/span>\nconsole<\/span>.<\/span>log<\/span>(<\/span>isEmptyObject<\/span>(<\/span>null<\/span>)<\/span>)<\/span>;<\/span> \/\/ true<\/span>\nconsole<\/span>.<\/span>log<\/span>(<\/span>isEmptyObject<\/span>(<\/span>undefined<\/span>)<\/span>)<\/span>;<\/span> \/\/ true<\/span>\nconsole<\/span>.<\/span>log<\/span>(<\/span>isEmptyObject<\/span>(<\/span>1<\/span>)<\/span>)<\/span>;<\/span> \/\/ true<\/span>\nconsole<\/span>.<\/span>log<\/span>(<\/span>isEmptyObject<\/span>(<\/span>''<\/span>)<\/span>)<\/span>;<\/span> \/\/ true<\/span>\nconsole<\/span>.<\/span>log<\/span>(<\/span>isEmptyObject<\/span>(<\/span>true<\/span>)<\/span>)<\/span>;<\/span> \/\/ true<\/span><\/pre>\n<\/div>\n
\u4ee5\u4e0a\u90fd\u4f1a\u8fd4\u56de true\u3002<\/p>\n
\u4f46\u662f\u65e2\u7136 jQuery \u662f\u8fd9\u6837\u5199\uff0c\u53ef\u80fd\u662f\u56e0\u4e3a\u8003\u8651\u5230\u5b9e\u9645\u5f00\u53d1\u4e2d isEmptyObject \u7528\u6765\u5224\u65ad {} \u548c {a: 1} \u662f\u8db3\u591f\u7684\u5427\u3002\u5982\u679c\u771f\u7684\u662f\u53ea\u5224\u65ad {}\uff0c\u5b8c\u5168\u53ef\u4ee5\u7ed3\u5408\u4e0a\u7bc7\u5199\u7684 type \u51fd\u6570\u7b5b\u9009\u6389\u4e0d\u9002\u5408\u7684\u60c5\u51b5\u3002<\/p>\n
Window\u5bf9\u8c61<\/h2>\n
Window \u5bf9\u8c61\u4f5c\u4e3a\u5ba2\u6237\u7aef JavaScript \u7684\u5168\u5c40\u5bf9\u8c61\uff0c\u5b83\u6709\u4e00\u4e2a window \u5c5e\u6027\u6307\u5411\u81ea\u8eab\uff0c\u8fd9\u70b9\u5728\u300aJavaScript\u6df1\u5165\u4e4b\u53d8\u91cf\u5bf9\u8c61\u300b<\/a>\u4e2d\u8bb2\u5230\u8fc7\u3002\u6211\u4eec\u53ef\u4ee5\u5229\u7528\u8fd9\u4e2a\u7279\u6027\u5224\u65ad\u662f\u5426\u662f Window \u5bf9\u8c61\u3002<\/p>\n
<\/p>\n
function<\/span> isWindow<\/span>(<\/span> obj<\/span> )<\/span> {<\/span>\n    return<\/span> obj<\/span> !=<\/span> null<\/span> &&<\/span> obj<\/span> ===<\/span> obj<\/span>.<\/span>window<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
isArrayLike<\/h2>\n
isArrayLike\uff0c\u770b\u540d\u5b57\u53ef\u80fd\u4f1a\u8ba9\u6211\u4eec\u89c9\u5f97\u8fd9\u662f\u5224\u65ad\u7c7b\u6570\u7ec4\u5bf9\u8c61\u7684\uff0c\u5176\u5b9e\u4e0d\u4ec5\u4ec5\u662f\u8fd9\u6837\uff0cjQuery \u5b9e\u73b0\u7684 isArrayLike\uff0c\u6570\u7ec4\u548c\u7c7b\u6570\u7ec4\u90fd\u4f1a\u8fd4\u56de true\u3002<\/p>\n
\u56e0\u4e3a\u6e90\u7801\u6bd4\u8f83\u7b80\u5355\uff0c\u6211\u4eec\u76f4\u63a5\u770b\u6e90\u7801\uff1a<\/p>\n
<\/p>\n
function<\/span> isArrayLike<\/span>(<\/span>obj<\/span>)<\/span> {<\/span>\n\n    \/\/ obj \u5fc5\u987b\u6709 length\u5c5e\u6027<\/span>\n    var<\/span> length<\/span> =<\/span> !<\/span>!<\/span>obj<\/span> &&<\/span> \"length\"<\/span> in<\/span> obj<\/span> &&<\/span> obj<\/span>.<\/span>length<\/span>;<\/span>\n    var<\/span> typeRes<\/span> =<\/span> type<\/span>(<\/span>obj<\/span>)<\/span>;<\/span>\n\n    \/\/ \u6392\u9664\u6389\u51fd\u6570\u548c Window \u5bf9\u8c61<\/span>\n    if<\/span> (<\/span>typeRes<\/span> ===<\/span> \"function\"<\/span> ||<\/span> isWindow<\/span>(<\/span>obj<\/span>)<\/span>)<\/span> {<\/span>\n        return<\/span> false<\/span>;<\/span>\n    }<\/span>\n\n    return<\/span> typeRes<\/span> ===<\/span> \"array\"<\/span> ||<\/span> length<\/span> ===<\/span> 0<\/span> ||<\/span>\n        typeof<\/span> length<\/span> ===<\/span> \"number\"<\/span> &&<\/span> length<\/span> ><\/span> 0<\/span> &&<\/span> (<\/span>length<\/span> -<\/span> 1<\/span>)<\/span> in<\/span> obj<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u91cd\u70b9\u5206\u6790 return \u8fd9\u4e00\u884c\uff0c\u4f7f\u7528\u4e86\u6216\u8bed\u53e5\uff0c\u53ea\u8981\u4e00\u4e2a\u4e3a true\uff0c\u7ed3\u679c\u5c31\u8fd4\u56de true\u3002<\/p>\n
\u6240\u4ee5\u5982\u679c isArrayLike \u8fd4\u56detrue\uff0c\u81f3\u5c11\u8981\u6ee1\u8db3\u4e09\u4e2a\u6761\u4ef6\u4e4b\u4e00\uff1a<\/p>\n
    \n
  1. \u662f\u6570\u7ec4<\/li>\n
  2. \u957f\u5ea6\u4e3a 0<\/li>\n
  3. lengths \u5c5e\u6027\u662f\u5927\u4e8e 0 \u7684\u6570\u5b57\u7c7b\u578b\uff0c\u5e76\u4e14obj[length – 1]\u5fc5\u987b\u5b58\u5728<\/li>\n<\/ol>\n
    \u7b2c\u4e00\u4e2a\u5c31\u4e0d\u8bf4\u4e86\uff0c\u770b\u7b2c\u4e8c\u4e2a\uff0c\u4e3a\u4ec0\u4e48\u957f\u5ea6\u4e3a 0 \u5c31\u53ef\u4ee5\u76f4\u63a5\u5224\u65ad\u4e3a true \u5462\uff1f<\/p>\n
    \u90a3\u6211\u4eec\u5199\u4e2a\u5bf9\u8c61\uff1a<\/p>\n
    \n
    var<\/span> obj<\/span> =<\/span> {<\/span>a<\/span>: 1<\/span>,<\/span> b<\/span>: 2<\/span>,<\/span> length<\/span>: 0<\/span>}<\/span><\/pre>\n<\/div>\n
    isArrayLike \u51fd\u6570\u5c31\u4f1a\u8fd4\u56de true\uff0c\u90a3\u8fd9\u4e2a\u5408\u7406\u5417\uff1f<\/p>\n
    \u56de\u7b54\u5408\u4e0d\u5408\u7406\u4e4b\u524d\uff0c\u6211\u4eec\u5148\u770b\u4e00\u4e2a\u4f8b\u5b50\uff1a<\/p>\n
    <\/p>\n
    function<\/span> a<\/span>(<\/span>)<\/span>{<\/span>\n    console<\/span>.<\/span>log<\/span>(<\/span>isArrayLike<\/span>(<\/span>arguments<\/span>)<\/span>)<\/span>\n}<\/span>\na<\/span>(<\/span>)<\/span>;<\/span><\/pre>\n<\/div>\n
    \u5982\u679c\u6211\u4eec\u53bb\u6389length === 0 \u8fd9\u4e2a\u5224\u65ad\uff0c\u5c31\u4f1a\u6253\u5370 false\uff0c\u7136\u800c\u6211\u4eec\u90fd\u77e5\u9053 arguments \u662f\u4e00\u4e2a\u7c7b\u6570\u7ec4\u5bf9\u8c61\uff0c\u8fd9\u91cc\u662f\u5e94\u8be5\u8fd4\u56de true \u7684\u3002<\/p>\n
    \u6240\u4ee5\u662f\u4e0d\u662f\u4e3a\u4e86\u653e\u8fc7\u7a7a\u7684 arguments \u65f6\u4e5f\u653e\u8fc7\u4e86\u4e00\u4e9b\u5b58\u5728\u4e89\u8bae\u7684\u5bf9\u8c61\u5462\uff1f<\/p>\n
    \u7b2c\u4e09\u4e2a\u6761\u4ef6\uff1alength \u662f\u6570\u5b57\uff0c\u5e76\u4e14 length > 0 \u4e14\u6700\u540e\u4e00\u4e2a\u5143\u7d20\u5b58\u5728\u3002<\/p>\n
    \u4e3a\u4ec0\u4e48\u4ec5\u4ec5\u8981\u6c42\u6700\u540e\u4e00\u4e2a\u5143\u7d20\u5b58\u5728\u5462\uff1f<\/p>\n
    \u8ba9\u6211\u4eec\u5148\u60f3\u4e0b\u6570\u7ec4\u662f\u4e0d\u662f\u53ef\u4ee5\u8fd9\u6837\u5199\uff1a<\/p>\n
    \n
    var<\/span> arr<\/span> =<\/span> [<\/span>,<\/span>,<\/span>3<\/span>]<\/span><\/pre>\n<\/div>\n
    \u5f53\u6211\u4eec\u5199\u4e00\u4e2a\u5bf9\u5e94\u7684\u7c7b\u6570\u7ec4\u5bf9\u8c61\u5c31\u662f\uff1a<\/p>\n
    <\/p>\n
    var<\/span> arrLike<\/span> =<\/span> {<\/span>\n    2<\/span>: 3<\/span>,<\/span>\n    length<\/span>: 3<\/span>\n}<\/span><\/pre>\n<\/div>\n
    \u4e5f\u5c31\u662f\u8bf4\u5f53\u6211\u4eec\u5728\u6570\u7ec4\u4e2d\u7528\u9017\u53f7\u76f4\u63a5\u8df3\u8fc7\u7684\u65f6\u5019\uff0c\u6211\u4eec\u8ba4\u4e3a\u8be5\u5143\u7d20\u662f\u4e0d\u5b58\u5728\u7684\uff0c\u7c7b\u6570\u7ec4\u5bf9\u8c61\u4e2d\u4e5f\u5c31\u4e0d\u7528\u5199\u8fd9\u4e2a\u5143\u7d20\uff0c\u4f46\u662f\u6700\u540e\u4e00\u4e2a\u5143\u7d20\u662f\u4e00\u5b9a\u8981\u5199\u7684\uff0c\u8981\u4e0d\u7136 length \u7684\u957f\u5ea6\u5c31\u4e0d\u4f1a\u662f\u6700\u540e\u4e00\u4e2a\u5143\u7d20\u7684 key \u503c\u52a0 1\u3002\u6bd4\u5982\u6570\u7ec4\u53ef\u4ee5\u8fd9\u6837\u5199<\/p>\n
    <\/p>\n
    var<\/span> arr<\/span> =<\/span> [<\/span>1<\/span>,<\/span>,<\/span>]<\/span>;<\/span>\nconsole<\/span>.<\/span>log<\/span>(<\/span>arr<\/span>.<\/span>length<\/span>)<\/span> \/\/ 2<\/span><\/pre>\n<\/div>\n
    \u4f46\u662f\u7c7b\u6570\u7ec4\u5bf9\u8c61\u5c31\u53ea\u80fd\u5199\u6210\uff1a<\/p>\n
    <\/p>\n
    var<\/span> arrLike<\/span> =<\/span> {<\/span>\n    0<\/span>: 1<\/span>,<\/span>\n    length<\/span>: 1<\/span>\n}<\/span><\/pre>\n<\/div>\n
    \u6240\u4ee5\u7b26\u5408\u6761\u4ef6\u7684\u7c7b\u6570\u7ec4\u5bf9\u8c61\u662f\u4e00\u5b9a\u5b58\u5728\u6700\u540e\u4e00\u4e2a\u5143\u7d20\u7684\uff01<\/p>\n
    \u8fd9\u5c31\u662f\u6ee1\u8db3 isArrayLike \u7684\u4e09\u4e2a\u6761\u4ef6\uff0c\u5176\u5b9e\u9664\u4e86 jQuery \u4e4b\u5916\uff0c\u5f88\u591a\u5e93\u90fd\u6709\u5bf9 isArrayLike \u7684\u5b9e\u73b0\uff0c\u6bd4\u5982 underscore:<\/p>\n
    <\/p>\n
    var<\/span> MAX_ARRAY_INDEX<\/span> =<\/span> Math<\/span>.<\/span>pow<\/span>(<\/span>2<\/span>,<\/span> 53<\/span>)<\/span> -<\/span> 1<\/span>;<\/span>\n\nvar<\/span> isArrayLike<\/span> =<\/span> function<\/span>(<\/span>collection<\/span>)<\/span> {<\/span>\n    var<\/span> length<\/span> =<\/span> getLength<\/span>(<\/span>collection<\/span>)<\/span>;<\/span>\n    return<\/span> typeof<\/span> length<\/span> ==<\/span> 'number'<\/span> &&<\/span> length<\/span> >=<\/span> 0<\/span> &&<\/span> length<\/span> <=<\/span> MAX_ARRAY_INDEX<\/span>;<\/span>\n}<\/span>;<\/span><\/pre>\n<\/div>\n
    isElement<\/h2>\n
    isElement \u5224\u65ad\u662f\u4e0d\u662f DOM \u5143\u7d20\u3002<\/p>\n
    <\/p>\n
    isElement<\/span> =<\/span> function<\/span>(<\/span>obj<\/span>)<\/span> {<\/span>\n    return<\/span> !<\/span>!<\/span>(<\/span>obj<\/span> &&<\/span> obj<\/span>.<\/span>nodeType<\/span> ===<\/span> 1<\/span>)<\/span>;<\/span>\n}<\/span>;<\/span><\/pre>\n<\/div>\n
    \u7ed3\u8bed<\/h2>\n
    \u8fd9\u4e00\u7bc7\u6211\u4eec\u4ecb\u7ecd\u4e86 jQuery \u7684 isPlainObject\u3001isEmptyObject\u3001isWindow\u3001isArrayLike\u3001\u4ee5\u53ca underscore \u7684 isElement \u5b9e\u73b0\u3002\u6211\u4eec\u53ef\u4ee5\u770b\u5230\uff0c\u5373\u4f7f\u662f jQuery \u8fd9\u6837\u4f18\u79c0\u7684\u5e93\uff0c\u4e00\u4e9b\u65b9\u6cd5\u7684\u5b9e\u73b0\u4e5f\u5e76\u4e0d\u662f\u975e\u5e38\u5b8c\u7f8e\u548c\u4e25\u5bc6\u7684\uff0c\u4f46\u662f\u6700\u540e\u4e3a\u4ec0\u4e48\u8fd9\u4e48\u505a\uff0c\u5176\u5b9e\u4e5f\u662f\u4e00\u79cd\u6743\u8861\uff0c\u6743\u8861\u6240\u5931\u4e0e\u6240\u5f97\uff0c\u6b63\u5982\u7389\u4f2f\u5728\u300a\u4ece JavaScript \u6570\u7ec4\u53bb\u91cd\u8c08\u6027\u80fd\u4f18\u5316\u300b\u4e2d\u8bb2\u5230\uff1a<\/p>\n
    \u6240\u6709\u8fd9\u4e9b\u70b9\uff0c\u90fd\u5fc5\u987b\u811a\u8e0f\u5b9e\u5730\u5728\u5177\u4f53\u5e94\u7528\u573a\u666f\u4e0b\u53bb\u5206\u6790\u3001\u53bb\u9009\u62e9\uff0c\u8981\u8ba9\u573a\u666f\u8bf4\u8bdd\u3002<\/strong><\/p>\n
    \u4e13\u9898\u7cfb\u5217<\/h2>\n
    JavaScript\u4e13\u9898\u7cfb\u5217\u76ee\u5f55\u5730\u5740\uff1ahttps:\/\/github.com\/mqyqingfeng\/Blog<\/a>\u3002<\/p>\n
    JavaScript\u4e13\u9898\u7cfb\u5217\u9884\u8ba1\u5199\u4e8c\u5341\u7bc7\u5de6\u53f3\uff0c\u4e3b\u8981\u7814\u7a76\u65e5\u5e38\u5f00\u53d1\u4e2d\u4e00\u4e9b\u529f\u80fd\u70b9\u7684\u5b9e\u73b0\uff0c\u6bd4\u5982\u9632\u6296\u3001\u8282\u6d41\u3001\u53bb\u91cd\u3001\u7c7b\u578b\u5224\u65ad\u3001\u62f7\u8d1d\u3001\u6700\u503c\u3001\u6241\u5e73\u3001\u67ef\u91cc\u3001\u9012\u5f52\u3001\u4e71\u5e8f\u3001\u6392\u5e8f\u7b49\uff0c\u7279\u70b9\u662f\u7814(chao)\u7a76(xi) underscore \u548c jQuery \u7684\u5b9e\u73b0\u65b9\u5f0f\u3002<\/p>\n<\/td>\n
    \u6587\u7ae0\u8f6c\u8f7d\u81eahttps:\/\/github.com\/mqyqingfeng\/Blog\/issues\/30<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
    \u524d\u8a00 \u5728\u4e0a\u7bc7\u300aJavaScript\u4e13\u9898\u4e4b\u7c7b\u578b\u5224\u65ad(\u4e0a)\u300b\u4e2d\uff0c\u6211\u4eec\u6284\u88ad jQuery \u5199\u4e86\u4e00\u4e2a type \u51fd\u6570\uff0c\u53ef\u4ee5\u68c0\u6d4b\u51fa\u5e38\u89c1\u7684\u6570\u636e\u7c7b\u578b\uff0c\u7136\u800c\u5728\u5f00\u53d1\u4e2d\u8fd8\u6709\u66f4\u52a0\u590d\u6742…<\/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-1379","post","type-post","status-publish","format-standard","hentry","category-learn"],"_links":{"self":[{"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/posts\/1379"}],"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=1379"}],"version-history":[{"count":1,"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/posts\/1379\/revisions"}],"predecessor-version":[{"id":1462,"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/posts\/1379\/revisions\/1462"}],"wp:attachment":[{"href":"https:\/\/www.lccc.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1379"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lccc.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1379"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lccc.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1379"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}