{"id":1390,"date":"2024-06-02T22:33:35","date_gmt":"2024-06-02T22:33:35","guid":{"rendered":""},"modified":"2024-06-05T06:12:19","modified_gmt":"2024-06-04T22:12:19","slug":"javascript%e6%b7%b1%e5%85%a5%e4%b9%8b%e6%89%a7%e8%a1%8c%e4%b8%8a%e4%b8%8b%e6%96%87%e6%a0%88","status":"publish","type":"post","link":"https:\/\/www.lccc.top\/?p=1390","title":{"rendered":"JavaScript\u6df1\u5165\u4e4b\u6267\u884c\u4e0a\u4e0b\u6587\u6808"},"content":{"rendered":"\n

\u987a\u5e8f\u6267\u884c\uff1f<\/h2>\n

\u5982\u679c\u8981\u95ee\u5230 JavaScript \u4ee3\u7801\u6267\u884c\u987a\u5e8f\u7684\u8bdd\uff0c\u60f3\u5fc5\u5199\u8fc7 JavaScript \u7684\u5f00\u53d1\u8005\u90fd\u4f1a\u6709\u4e2a\u76f4\u89c2\u7684\u5370\u8c61\uff0c\u90a3\u5c31\u662f\u987a\u5e8f\u6267\u884c\uff0c\u6bd5\u7adf\uff1a<\/p>\n

<\/p>\n
var<\/span> foo<\/span> =<\/span> function<\/span> (<\/span>)<\/span> {<\/span>\n\n    console<\/span>.<\/span>log<\/span>(<\/span>'foo1'<\/span>)<\/span>;<\/span>\n\n}<\/span>\n\nfoo<\/span>(<\/span>)<\/span>;<\/span>  \/\/ foo1<\/span>\n\nvar<\/span> foo<\/span> =<\/span> function<\/span> (<\/span>)<\/span> {<\/span>\n\n    console<\/span>.<\/span>log<\/span>(<\/span>'foo2'<\/span>)<\/span>;<\/span>\n\n}<\/span>\n\nfoo<\/span>(<\/span>)<\/span>;<\/span> \/\/ foo2<\/span><\/pre>\n<\/div>\n
\u7136\u800c\u53bb\u770b\u8fd9\u6bb5\u4ee3\u7801\uff1a<\/p>\n
<\/p>\n
function<\/span> foo<\/span>(<\/span>)<\/span> {<\/span>\n\n    console<\/span>.<\/span>log<\/span>(<\/span>'foo1'<\/span>)<\/span>;<\/span>\n\n}<\/span>\n\nfoo<\/span>(<\/span>)<\/span>;<\/span>  \/\/ foo2<\/span>\n\nfunction<\/span> foo<\/span>(<\/span>)<\/span> {<\/span>\n\n    console<\/span>.<\/span>log<\/span>(<\/span>'foo2'<\/span>)<\/span>;<\/span>\n\n}<\/span>\n\nfoo<\/span>(<\/span>)<\/span>;<\/span> \/\/ foo2<\/span><\/pre>\n<\/div>\n
\u6253\u5370\u7684\u7ed3\u679c\u5374\u662f\u4e24\u4e2a foo2<\/code>\u3002<\/p>\n
\u5237\u8fc7\u9762\u8bd5\u9898\u7684\u90fd\u77e5\u9053\u8fd9\u662f\u56e0\u4e3a JavaScript \u5f15\u64ce\u5e76\u975e\u4e00\u884c\u4e00\u884c\u5730\u5206\u6790\u548c\u6267\u884c\u7a0b\u5e8f\uff0c\u800c\u662f\u4e00\u6bb5\u4e00\u6bb5\u5730\u5206\u6790\u6267\u884c\u3002\u5f53\u6267\u884c\u4e00\u6bb5\u4ee3\u7801\u7684\u65f6\u5019\uff0c\u4f1a\u8fdb\u884c\u4e00\u4e2a\u201c\u51c6\u5907\u5de5\u4f5c\u201d\uff0c\u6bd4\u5982\u7b2c\u4e00\u4e2a\u4f8b\u5b50\u4e2d\u7684\u53d8\u91cf\u63d0\u5347\uff0c\u548c\u7b2c\u4e8c\u4e2a\u4f8b\u5b50\u4e2d\u7684\u51fd\u6570\u63d0\u5347\u3002<\/p>\n
\u4f46\u662f\u672c\u6587\u771f\u6b63\u60f3\u8ba9\u5927\u5bb6\u601d\u8003\u7684\u662f\uff1a\u8fd9\u4e2a\u201c\u4e00\u6bb5\u4e00\u6bb5\u201d\u4e2d\u7684\u201c\u6bb5\u201d\u7a76\u7adf\u662f\u600e\u4e48\u5212\u5206\u7684\u5462\uff1f<\/p>\n
\u5230\u5e95JavaScript\u5f15\u64ce\u9047\u5230\u4e00\u6bb5\u600e\u6837\u7684\u4ee3\u7801\u65f6\u624d\u4f1a\u505a\u201c\u51c6\u5907\u5de5\u4f5c\u201d\u5462\uff1f<\/p>\n
\u53ef\u6267\u884c\u4ee3\u7801<\/h2>\n
\u8fd9\u5c31\u8981\u8bf4\u5230 JavaScript \u7684\u53ef\u6267\u884c\u4ee3\u7801(executable code)\u7684\u7c7b\u578b\u6709\u54ea\u4e9b\u4e86\uff1f<\/p>\n
\u5176\u5b9e\u5f88\u7b80\u5355\uff0c\u5c31\u4e09\u79cd\uff0c\u5168\u5c40\u4ee3\u7801\u3001\u51fd\u6570\u4ee3\u7801\u3001eval\u4ee3\u7801\u3002<\/p>\n
\u4e3e\u4e2a\u4f8b\u5b50\uff0c\u5f53\u6267\u884c\u5230\u4e00\u4e2a\u51fd\u6570\u7684\u65f6\u5019\uff0c\u5c31\u4f1a\u8fdb\u884c\u51c6\u5907\u5de5\u4f5c\uff0c\u8fd9\u91cc\u7684\u201c\u51c6\u5907\u5de5\u4f5c\u201d\uff0c\u8ba9\u6211\u4eec\u7528\u4e2a\u66f4\u4e13\u4e1a\u4e00\u70b9\u7684\u8bf4\u6cd5\uff0c\u5c31\u53eb\u505a”\u6267\u884c\u4e0a\u4e0b\u6587(execution context)”\u3002<\/p>\n
\u6267\u884c\u4e0a\u4e0b\u6587\u6808<\/h2>\n
\u63a5\u4e0b\u6765\u95ee\u9898\u6765\u4e86\uff0c\u6211\u4eec\u5199\u7684\u51fd\u6570\u591a\u4e86\u53bb\u4e86\uff0c\u5982\u4f55\u7ba1\u7406\u521b\u5efa\u7684\u90a3\u4e48\u591a\u6267\u884c\u4e0a\u4e0b\u6587\u5462\uff1f<\/p>\n
\u6240\u4ee5 JavaScript \u5f15\u64ce\u521b\u5efa\u4e86\u6267\u884c\u4e0a\u4e0b\u6587\u6808\uff08Execution context stack\uff0cECS\uff09\u6765\u7ba1\u7406\u6267\u884c\u4e0a\u4e0b\u6587<\/p>\n
\u4e3a\u4e86\u6a21\u62df\u6267\u884c\u4e0a\u4e0b\u6587\u6808\u7684\u884c\u4e3a\uff0c\u8ba9\u6211\u4eec\u5b9a\u4e49\u6267\u884c\u4e0a\u4e0b\u6587\u6808\u662f\u4e00\u4e2a\u6570\u7ec4\uff1a<\/p>\n
\n
ECStack<\/span> =<\/span> [<\/span>]<\/span>;<\/span><\/pre>\n<\/div>\n
\u8bd5\u60f3\u5f53 JavaScript \u5f00\u59cb\u8981\u89e3\u91ca\u6267\u884c\u4ee3\u7801\u7684\u65f6\u5019\uff0c\u6700\u5148\u9047\u5230\u7684\u5c31\u662f\u5168\u5c40\u4ee3\u7801\uff0c\u6240\u4ee5\u521d\u59cb\u5316\u7684\u65f6\u5019\u9996\u5148\u5c31\u4f1a\u5411\u6267\u884c\u4e0a\u4e0b\u6587\u6808\u538b\u5165\u4e00\u4e2a\u5168\u5c40\u6267\u884c\u4e0a\u4e0b\u6587\uff0c\u6211\u4eec\u7528 globalContext \u8868\u793a\u5b83\uff0c\u5e76\u4e14\u53ea\u6709\u5f53\u6574\u4e2a\u5e94\u7528\u7a0b\u5e8f\u7ed3\u675f\u7684\u65f6\u5019\uff0cECStack \u624d\u4f1a\u88ab\u6e05\u7a7a\uff0c\u6240\u4ee5\u7a0b\u5e8f\u7ed3\u675f\u4e4b\u524d\uff0c ECStack \u6700\u5e95\u90e8\u6c38\u8fdc\u6709\u4e2a globalContext\uff1a<\/p>\n
<\/p>\n
ECStack<\/span> =<\/span> [<\/span>\n    globalContext<\/span>\n]<\/span>;<\/span><\/pre>\n<\/div>\n
\u73b0\u5728 JavaScript \u9047\u5230\u4e0b\u9762\u7684\u8fd9\u6bb5\u4ee3\u7801\u4e86\uff1a<\/p>\n
<\/p>\n
function<\/span> fun3<\/span>(<\/span>)<\/span> {<\/span>\n    console<\/span>.<\/span>log<\/span>(<\/span>'fun3'<\/span>)<\/span>\n}<\/span>\n\nfunction<\/span> fun2<\/span>(<\/span>)<\/span> {<\/span>\n    fun3<\/span>(<\/span>)<\/span>;<\/span>\n}<\/span>\n\nfunction<\/span> fun1<\/span>(<\/span>)<\/span> {<\/span>\n    fun2<\/span>(<\/span>)<\/span>;<\/span>\n}<\/span>\n\nfun1<\/span>(<\/span>)<\/span>;<\/span><\/pre>\n<\/div>\n
\u5f53\u6267\u884c\u4e00\u4e2a\u51fd\u6570\u7684\u65f6\u5019\uff0c\u5c31\u4f1a\u521b\u5efa\u4e00\u4e2a\u6267\u884c\u4e0a\u4e0b\u6587\uff0c\u5e76\u4e14\u538b\u5165\u6267\u884c\u4e0a\u4e0b\u6587\u6808\uff0c\u5f53\u51fd\u6570\u6267\u884c\u5b8c\u6bd5\u7684\u65f6\u5019\uff0c\u5c31\u4f1a\u5c06\u51fd\u6570\u7684\u6267\u884c\u4e0a\u4e0b\u6587\u4ece\u6808\u4e2d\u5f39\u51fa\u3002\u77e5\u9053\u4e86\u8fd9\u6837\u7684\u5de5\u4f5c\u539f\u7406\uff0c\u8ba9\u6211\u4eec\u6765\u770b\u770b\u5982\u4f55\u5904\u7406\u4e0a\u9762\u8fd9\u6bb5\u4ee3\u7801\uff1a<\/p>\n
<\/p>\n
\/\/ \u4f2a\u4ee3\u7801<\/span>\n\n\/\/ fun1()<\/span>\nECStack<\/span>.<\/span>push<\/span>(<\/span><<\/span>fun1<\/span>><\/span> functionContext);\n\n\/\/ fun1\u4e2d\u7adf\u7136\u8c03\u7528\u4e86fun2\uff0c\u8fd8\u8981\u521b\u5efafun2\u7684\u6267\u884c\u4e0a\u4e0b\u6587\nECStack.push(<<\/span>fun2<\/span>><\/span> functionContext);\n\n\/\/ \u64e6\uff0cfun2\u8fd8\u8c03\u7528\u4e86fun3\uff01\nECStack.push(<<\/span>fun3<\/span>><\/span> functionContext);\n\n\/\/ fun3\u6267\u884c\u5b8c\u6bd5\nECStack.pop();\n\n\/\/ fun2\u6267\u884c\u5b8c\u6bd5\nECStack.pop();\n\n\/\/ fun1\u6267\u884c\u5b8c\u6bd5\nECStack.pop();\n\n\/\/ javascript\u63a5\u7740\u6267\u884c\u4e0b\u9762\u7684\u4ee3\u7801\uff0c\u4f46\u662fECStack\u5e95\u5c42\u6c38\u8fdc\u6709\u4e2aglobalContext<\/pre>\n<\/div>\n
\u89e3\u7b54\u601d\u8003\u9898<\/h2>\n
\u597d\u5566\uff0c\u73b0\u5728\u6211\u4eec\u5df2\u7ecf\u4e86\u89e3\u4e86\u6267\u884c\u4e0a\u4e0b\u6587\u6808\u662f\u5982\u4f55\u5904\u7406\u6267\u884c\u4e0a\u4e0b\u6587\u7684\uff0c\u6240\u4ee5\u8ba9\u6211\u4eec\u770b\u770b\u4e0a\u7bc7\u6587\u7ae0\u300aJavaScript\u6df1\u5165\u4e4b\u8bcd\u6cd5\u4f5c\u7528\u57df\u548c\u52a8\u6001\u4f5c\u7528\u57df\u300b<\/a>\u6700\u540e\u7684\u95ee\u9898\uff1a<\/p>\n
<\/p>\n
var<\/span> scope<\/span> =<\/span> \"global scope\"<\/span>;<\/span>\nfunction<\/span> checkscope<\/span>(<\/span>)<\/span>{<\/span>\n    var<\/span> scope<\/span> =<\/span> \"local scope\"<\/span>;<\/span>\n    function<\/span> f<\/span>(<\/span>)<\/span>{<\/span>\n        return<\/span> scope<\/span>;<\/span>\n    }<\/span>\n    return<\/span> f<\/span>(<\/span>)<\/span>;<\/span>\n}<\/span>\ncheckscope<\/span>(<\/span>)<\/span>;<\/span><\/pre>\n<\/div>\n
<\/p>\n
var<\/span> scope<\/span> =<\/span> \"global scope\"<\/span>;<\/span>\nfunction<\/span> checkscope<\/span>(<\/span>)<\/span>{<\/span>\n    var<\/span> scope<\/span> =<\/span> \"local scope\"<\/span>;<\/span>\n    function<\/span> f<\/span>(<\/span>)<\/span>{<\/span>\n        return<\/span> scope<\/span>;<\/span>\n    }<\/span>\n    return<\/span> f<\/span>;<\/span>\n}<\/span>\ncheckscope<\/span>(<\/span>)<\/span>(<\/span>)<\/span>;<\/span><\/pre>\n<\/div>\n
\u4e24\u6bb5\u4ee3\u7801\u6267\u884c\u7684\u7ed3\u679c\u4e00\u6837\uff0c\u4f46\u662f\u4e24\u6bb5\u4ee3\u7801\u7a76\u7adf\u6709\u54ea\u4e9b\u4e0d\u540c\u5462\uff1f<\/p>\n
\u7b54\u6848\u5c31\u662f\u6267\u884c\u4e0a\u4e0b\u6587\u6808\u7684\u53d8\u5316\u4e0d\u4e00\u6837\u3002<\/p>\n
\u8ba9\u6211\u4eec\u6a21\u62df\u7b2c\u4e00\u6bb5\u4ee3\u7801\uff1a<\/p>\n
<\/p>\n
ECStack<\/span>.<\/span>push<\/span>(<\/span><<\/span>checkscope<\/span>><\/span> functionContext);\nECStack.push(<<\/span>f<\/span>><\/span> functionContext);\nECStack.pop();\nECStack.pop();<\/pre>\n<\/div>\n
\u8ba9\u6211\u4eec\u6a21\u62df\u7b2c\u4e8c\u6bb5\u4ee3\u7801\uff1a<\/p>\n
<\/p>\n
ECStack<\/span>.<\/span>push<\/span>(<\/span><<\/span>checkscope<\/span>><\/span> functionContext);\nECStack.pop();\nECStack.push(<<\/span>f<\/span>><\/span> functionContext);\nECStack.pop();<\/pre>\n<\/div>\n
\u662f\u4e0d\u662f\u6709\u4e9b\u4e0d\u540c\u5462\uff1f<\/p>\n
\u5f53\u7136\u4e86\uff0c\u8fd9\u6837\u6982\u62ec\u7684\u56de\u7b54\u6267\u884c\u4e0a\u4e0b\u6587\u6808\u7684\u53d8\u5316\u4e0d\u540c\uff0c\u662f\u4e0d\u662f\u4f9d\u7136\u6709\u4e00\u79cd\u610f\u72b9\u672a\u5c3d\u7684\u611f\u89c9\u5462\uff0c\u4e3a\u4e86\u66f4\u8be6\u7ec6\u8bb2\u89e3\u4e24\u4e2a\u51fd\u6570\u6267\u884c\u4e0a\u7684\u533a\u522b\uff0c\u6211\u4eec\u9700\u8981\u63a2\u7a76\u4e00\u4e0b\u6267\u884c\u4e0a\u4e0b\u6587\u5230\u5e95\u5305\u542b\u4e86\u54ea\u4e9b\u5185\u5bb9\uff0c\u6240\u4ee5\u6b22\u8fce\u9605\u8bfb\u4e0b\u4e00\u7bc7\u300aJavaScript\u6df1\u5165\u4e4b\u53d8\u91cf\u5bf9\u8c61\u300b\u3002<\/p>\n
\u4e0b\u4e00\u7bc7\u6587\u7ae0<\/h2>\n
\u300aJavaScript\u6df1\u5165\u4e4b\u53d8\u91cf\u5bf9\u8c61\u300b<\/a><\/p>\n
\u6df1\u5165\u7cfb\u5217<\/h2>\n
JavaScript\u6df1\u5165\u7cfb\u5217\u76ee\u5f55\u5730\u5740\uff1ahttps:\/\/github.com\/mqyqingfeng\/Blog<\/a>\u3002<\/p>\n
JavaScript\u6df1\u5165\u7cfb\u5217\u9884\u8ba1\u5199\u5341\u4e94\u7bc7\u5de6\u53f3\uff0c\u65e8\u5728\u5e2e\u5927\u5bb6\u634b\u987aJavaScript\u5e95\u5c42\u77e5\u8bc6\uff0c\u91cd\u70b9\u8bb2\u89e3\u5982\u539f\u578b\u3001\u4f5c\u7528\u57df\u3001\u6267\u884c\u4e0a\u4e0b\u6587\u3001\u53d8\u91cf\u5bf9\u8c61\u3001this\u3001\u95ed\u5305\u3001\u6309\u503c\u4f20\u9012\u3001call\u3001apply\u3001bind\u3001new\u3001\u7ee7\u627f\u7b49\u96be\u70b9\u6982\u5ff5\u3002<\/p>\n
\u5982\u679c\u6709\u9519\u8bef\u6216\u8005\u4e0d\u4e25\u8c28\u7684\u5730\u65b9\uff0c\u8bf7\u52a1\u5fc5\u7ed9\u4e88\u6307\u6b63\uff0c\u5341\u5206\u611f\u8c22\u3002\u5982\u679c\u559c\u6b22\u6216\u8005\u6709\u6240\u542f\u53d1\uff0c\u6b22\u8fcestar\uff0c\u5bf9\u4f5c\u8005\u4e5f\u662f\u4e00\u79cd\u9f13\u52b1\u3002<\/p>\n<\/td>\n
\u6587\u7ae0\u8f6c\u8f7d\u81eahttps:\/\/github.com\/mqyqingfeng\/Blog\/issues\/4<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
\u987a\u5e8f\u6267\u884c\uff1f \u5982\u679c\u8981\u95ee\u5230 JavaScript \u4ee3\u7801\u6267\u884c\u987a\u5e8f\u7684\u8bdd\uff0c\u60f3\u5fc5\u5199\u8fc7 JavaScript \u7684\u5f00\u53d1\u8005\u90fd\u4f1a\u6709\u4e2a\u76f4\u89c2\u7684\u5370\u8c61\uff0c\u90a3\u5c31\u662f\u987a\u5e8f\u6267\u884c\uff0c\u6bd5\u7adf\uff1a var fo…<\/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-1390","post","type-post","status-publish","format-standard","hentry","category-learn"],"_links":{"self":[{"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/posts\/1390"}],"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=1390"}],"version-history":[{"count":1,"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/posts\/1390\/revisions"}],"predecessor-version":[{"id":1491,"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/posts\/1390\/revisions\/1491"}],"wp:attachment":[{"href":"https:\/\/www.lccc.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1390"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lccc.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1390"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lccc.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1390"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}