{"id":1120,"date":"2022-04-30T10:26:07","date_gmt":"2022-04-30T02:26:07","guid":{"rendered":"http:\/\/zhuxinyong.com\/?p=1120"},"modified":"2023-02-16T14:40:45","modified_gmt":"2023-02-16T06:40:45","slug":"14-javascript-zhong-de-bi-bao","status":"publish","type":"post","link":"https:\/\/zhuxinyong.com\/?p=1120","title":{"rendered":"14 – JavaScript \u4e2d\u7684\u95ed\u5305"},"content":{"rendered":"

\"\"<\/p>\n

\u539f\u6587\u5730\u5740\uff1ahttps:\/\/dev.to\/bhagatparwinder\/closures-in-javascript-1f6k<\/a><\/p>\n

<\/span><\/a>\u4ec0\u4e48\u662f\u95ed\u5305\uff1f<\/h3>\n

\u6211\u8ba4\u4e3a JavaScript \u4e2d\u7684\u95ed\u5305\u662f\u4e00\u4e2a\u9ad8\u7ea7\u8bdd\u9898\uff0c\u662f\u4e00\u4e2a\u9762\u8bd5\u4e2d\u7ecf\u5e38\u88ab\u63d0\u5230\u7684\u95ee\u9898\u3002<\/p>\n

\u82e5\u4f60\u8bfb\u4e86\u6211\u4e4b\u524d\u7684\u6587\u7ae0\u6216\u4e86\u89e3 JavaScript \u4e2d\u7684\u4f5c\u7528\u57df\uff0c\u90a3\u7406\u89e3\u95ed\u5305\u4f1a\u8f7b\u677e\u4e9b\u3002<\/p>\n

\u51fd\u6570\u4f5c\u7528\u57df\u662f\u6307\u51fd\u6570\u4e2d\u58f0\u660e\u7684\u53d8\u91cf\u53ea\u80fd\u5728\u51fd\u6570\u4e2d\u4f7f\u7528\uff0c\u540c\u6837\u4e5f\u53ef\u4ee5\u88ab\u5b83\u5185\u90e8\u7684\u51fd\u6570\u5f15\u7528\u5230\u3002\u4f46\u95ed\u5305\u66f4\u8fdb\u4e00\u6b65\uff0c\u5b83\u4f7f\u7236\u7ea7\u51fd\u6570\u7684\u4f5c\u7528\u57df\u5728\u6267\u884c\u7ed3\u675f\u540e\u4f9d\u65e7\u53ef\u4ee5\u88ab\u83b7\u5f97\u3002<\/p>\n

function outer() {\n    const outerVariable = "outer";\n    function inner() {\n        const innerVariable = "inner";\n        console.log(`${outerVariable} ${innerVariable}`); \/\/ outer inner\n    }\n    inner();\n}\n\nouter();\n<\/code><\/pre>\n
\u4e0a\u9762\u7684\u4f8b\u5b50\u4e2d\uff0c\u6211\u521b\u5efa\u5e76\u6267\u884c\u4e86\u51fd\u6570 outer<\/strong>\uff0c\u540c\u65f6\u5185\u90e8\u4e5f\u521b\u5efa\u548c\u8c03\u7528\u4e86 inner<\/strong> \u51fd\u6570\u3002inner<\/strong> \u51fd\u6570\u6210\u529f\u6253\u5370\u51fa\u4e86\u7236\u7ea7\u51fd\u6570\u4e2d\u58f0\u660e\u7684\u53d8\u91cf\u548c\u671f\u671b\u7684\u4e00\u6837\uff0c\u56e0\u4e3a\u5b50\u51fd\u6570\u53ef\u4ee5\u83b7\u53d6\u7236\u51fd\u6570\u7684\u4f5c\u7528\u57df\u3002<\/p>\n
\u73b0\u5728\u6211\u4eec\u6765\u8fd4\u56de inner \u51fd\u6570\u800c\u4e0d\u662f\u8c03\u7528\u5b83\u3002<\/p>\n
function outer() {\n    const outerVariable = "outer";\n    function inner() {\n        const innerVariable = "inner";\n        return (`${outerVariable} ${innerVariable}`);\n    }\n    return inner;\n}\n\nconst returnFunction = outer();\nconsole.log(returnFunction); \/\/ Function returnFunction\n<\/code><\/pre>\n
\u53d8\u91cf returnFunction<\/strong> \u662f\u4e00\u4e2a\u51fd\u6570\u56e0\u4e3a\u5b83\u662f outer \u8fd4\u56de\u7684\u3002\u4e0d\u8981\u60ca\u8bb6\u3002<\/p>\n
\u6b64\u65f6\uff0couter \u51fd\u6570\u5df2\u7ecf\u6267\u884c\u5b8c\u6bd5\uff0c\u8fd4\u56de\u7684\u503c\u8d4b\u503c\u7ed9\u4e86\u4e00\u4e2a\u65b0\u53d8\u91cf\u3002<\/em><\/p>\n
\u5f53\u4e00\u4e2a\u51fd\u6570\u4ece\u8c03\u7528\u6808\u4e2d\u88ab\u629b\u51fa\u65f6\uff0cJavaScript \u5783\u573e\u6536\u96c6\u5668\u6b64\u65f6\u5e94\u8be5\u5220\u9664\u4e86\u6240\u6709\u5bf9 outerVarible \u7684\u5f15\u7528\u3002\u6211\u4eec\u6765\u6267\u884c returnFunction\u3002<\/p>\n
function outer() {\n    const outerVariable = "outer";\n    function inner() {\n        const innerVariable = "inner";\n        return (`${outerVariable} ${innerVariable}`); \/\/ outer inner\n    }\n    return inner;\n}\n\nconst returnFunction = outer();\nconsole.log(returnFunction); \/\/ Function returnFunction\nconsole.log(returnFunction()); \/\/ outer inner\n<\/code><\/pre>\n
\u60ca\u4e0d\u60ca\u5947\uff0c\u610f\u4e0d\u610f\u5916\uff01\u5b83\u4f9d\u65e7\u53ef\u4ee5\u6253\u5370\u51fa\u7236\u51fd\u6570\u4e2d\u58f0\u660e\u7684\u53d8\u91cf\u5373\u4f7f\u7236\u51fd\u6570\u5df2\u7ecf\u6267\u884c\u5b8c\u3002<\/p>\n
JavaScript \u5783\u573e\u6536\u96c6\u5668\u5e76\u6ca1\u6709\u6e05\u9664\u7236\u51fd\u6570\u4e2d\u88ab\u5b50\u51fd\u6570\u8fd4\u56de\u7684\u53d8\u91cf\uff0c\u8fd9\u4e9b\u7a0d\u540e\u6267\u884c\u7684\u5b50\u51fd\u6570\u6839\u636e\u8bcd\u6cd5\u4f5c\u7528\u57df\u539f\u5219\u4f9d\u65e7\u53ef\u4ee5\u5f15\u7528\u7236\u51fd\u6570\u7684\u4f5c\u7528\u57df\u3002<\/p>\n
\u8fd9\u79cd\u5783\u573e\u6536\u96c6\u5668\u7684\u884c\u4e3a\u5e76\u4e0d\u4ec5\u4ec5\u5c40\u9650\u4e8e\u5b50\u51fd\u6570\uff0c\u82e5\u4e00\u4e2a\u53d8\u91cf\u53ea\u8981\u4efb\u4f55\u4e00\u4e2a\u4e1c\u897f\u5bf9\u5b83\u5b58\u5728\u5f15\u7528\u5c31\u4e0d\u4f1a\u88ab\u5783\u573e\u6536\u96c6\u5668\u56de\u6536\u3002<\/p>\n
<\/span><\/a>\u771f\u5b9e\u7684\u4f8b\u5b50<\/h3>\n
\u6211\u4eec\u5047\u8bbe\u6211\u5728\u7f16\u5199\u4e00\u4e2a\u5173\u4e8e\u6c7d\u8f66\u7684\u7a0b\u5e8f\uff0c\u8fd9\u8f86\u8f66\u53ef\u4ee5\u50cf\u771f\u5b9e\u4e16\u754c\u4e00\u6837\u52a0\u901f\uff0c\u53ea\u8981\u52a0\u901f\u6c7d\u8f66\u7684\u901f\u5ea6\u5c31\u4f1a\u63d0\u9ad8\u3002<\/p>\n
function carMonitor() {\n    var speed = 0;\n\n    return {\n        accelerate: function () {\n            return speed++;\n        }\n    }\n}\n\nvar car = new carMonitor();\nconsole.log(car.accelerate()); \/\/ 0\nconsole.log(car.accelerate()); \/\/ 1\nconsole.log(car.accelerate()); \/\/ 2\nconsole.log(car.accelerate()); \/\/ 3\nconsole.log(car.accelerate()); \/\/ 4\n<\/code><\/pre>\n
\u5982\u4f60\u6240\u89c1\uff0ccarMonitor \u4e2d\u58f0\u660e\u4e86\u6c7d\u8f66\u7684\u901f\u5ea6\uff0c\u540c\u65f6 accelerate \u51fd\u6570\u53ef\u4ee5\u5f15\u7528\u5b83\u3002\u6bcf\u6b21\u6211\u8c03\u7528 accelerate\u65f6\uff0c\u4e0d\u4ec5\u4ec5\u662f\u53ef\u4ee5\u83b7\u53d6\u53d8\u91cf\u800c\u4e14\u662f\u5728\u4e0a\u6b21\u7684\u503c\u57fa\u7840\u4e0a\u518d\u589e\u52a0\u7136\u540e\u8fd4\u56de\u3002<\/p>\n
<\/span><\/a>\u4f7f\u7528\u95ed\u5305\u521b\u5efa\u79c1\u6709\u53d8\u91cf<\/h4>\n
\u6211\u4eec\u7ee7\u7eed\u4f7f\u7528 carMonitore \u7684\u4f8b\u5b50\u3002<\/p>\n
function carMonitor() {\n    var speed = 0;\n\n    return {\n        accelerate: function () {\n            return speed++;\n        }\n    }\n}\n\nvar car = new carMonitor();\nconsole.log(car.accelerate()); \/\/ 0\nconsole.log(car.accelerate()); \/\/ 1\nconsole.log(car.accelerate()); \/\/ 2\nconsole.log(car.accelerate()); \/\/ 3\nconsole.log(car.accelerate()); \/\/ 4\nconsole.log(speed); \/\/ speed is not defined\n<\/code><\/pre>\n
\u4f60\u53ef\u4ee5\u770b\u89c1 speed \u662f carMonitor \u7684\u79c1\u6709\u53d8\u91cf\uff0c\u53ea\u80fd\u88ab\u5b50\u51fd\u6570 accelerate \u5f15\u7528\uff0c\u51fd\u6570\u5916\u90e8\u90fd\u4e0d\u80fd\u5f15\u7528\u5b83\u3002\u6709\u4eba\u53ef\u80fd\u4f1a\u4e89\u8fa9\u6b63\u56e0\u51fd\u6570\u4f5c\u7528\u57df\u624d\u4f1a\u5982\u6b64\u3002\u5b83\u662f carMonitor \u7684\u79c1\u6709\u53d8\u91cf\u540c\u65f6\u6bcf\u4e2a carMonitor \u5b9e\u4f8b\u7684\u79c1\u6709\u53d8\u91cf\u3002<\/p>\n
\n
\u6bcf\u4e2a\u5b9e\u4f8b\u90fd\u7ef4\u62a4\u7740\u5bf9\u5b83\u7684\u62f7\u8d1d\u3002<\/p>\n<\/blockquote>\n
\u8fd9\u53ef\u4ee5\u5e2e\u52a9\u4f60\u8ba4\u8bc6\u5230\u95ed\u5305\u7684\u5f3a\u5927\u3002<\/p>\n
function carMonitor() {\n    var speed = 0;\n\n    return {\n        accelerate: function () {\n            return speed++;\n        }\n    }\n}\n\nvar car = new carMonitor();\nvar redCar = new carMonitor()\nconsole.log(car.accelerate()); \/\/ 0\nconsole.log(car.accelerate()); \/\/ 1\nconsole.log(redCar.accelerate()); \/\/ 0\nconsole.log(redCar.accelerate()); \/\/ 1\nconsole.log(car.accelerate()); \/\/ 2\nconsole.log(redCar.accelerate()); \/\/ 2\nconsole.log(speed); \/\/ speed is not defined\n<\/code><\/pre>\n
car \u548c redCar \u7ef4\u62a4\u7740\u5b83\u4eec\u81ea\u5df1\u7684\u79c1\u6709 speed \u53d8\u91cf\uff0c\u540c\u65f6 speed \u5728\u5916\u90e8\u4e0d\u80fd\u88ab\u8bbf\u95ee\u3002<\/p>\n
\u6211\u4eec\u5f3a\u5236\u7528\u6237\u4f7f\u7528\u5b9a\u4e49\u5728\u51fd\u6570\u6216\u7c7b\u4e2d\u7684\u65b9\u6cd5\u6765\u6539\u53d8\u5c5e\u6027\u800c\u4e0d\u662f\u76f4\u63a5\u5f15\u7528\u5b83\uff0c\u8fd9\u5c31\u662f\u4f60\u5e94\u8be5\u5982\u6b64\u5c01\u88c5\u4ee3\u7801\u3002<\/p>\n
\u6211\u5e0c\u671b\u8fd9\u7bc7\u6587\u7ae0\u6e05\u9664\u4e86 JavaScript \u4e2d\u95ed\u5305\u7684\u4efb\u4f55\u7591\u95ee\u3002<\/p>\n
<\/span><\/a>\u5e38\u89c1\u9762\u8bd5\u95ee\u9898<\/h3>\n
\u4e0b\u9762\u662f\u4e00\u4e9b\u9762\u8bd5\u4e2d\u7ecf\u5e38\u95ee\u9053\u7684\u95ed\u5305\u95ee\u9898\uff1a<\/p>\n
\u4f60\u8ba4\u4e3a\u4e0b\u9762\u7684\u4ee3\u7801\u8f93\u51fa\u4ec0\u4e48\uff1a<\/p>\n
for (var i = 0; i <= 5; i++) {\n    setTimeout(function () {\n        console.log(i);\n    }, 1000);\n}\n<\/code><\/pre>\n
\u82e5\u4f60\u731c\u95f4\u9694\u4e00\u79d2\u6253\u5370\u51fa 0 \u5230 5\uff0c\u4f60\u4f1a\u611f\u5230\u60ca\u8bb6\u3002\u968f\u7740 setTimeout \u7684\u4e00\u79d2\u540e\uff0ci \u5df2\u7ecf\u53d8\u6210\u4e86 6 \uff01\u6211\u4eec\u5c06\u501f\u52a9\u95ed\u5305\u6765\u5e2e\u52a9\u4f60\u5b9e\u73b0\u9884\u671f\u7684\u7b54\u6848\uff1a<\/p>\n
for (var i = 0; i <= 5; i++) {\n    (function (i) {\n        setTimeout(function () {\n            console.log(i);\n        }, 1000);\n    })(i);\n}\n<\/code><\/pre>\n
\u8fd8\u6709\u53e6\u4e00\u4e2a\u89e3\u51b3\u95ee\u9898\u7684\u65b9\u6cd5\uff0c\u4f7f\u7528 let<\/strong> \u5173\u952e\u5b57\u3002<\/p>\n
\u5faa\u73af\u4e2d\u7684 var \u58f0\u660e\u4e86\u51fd\u6570\u4f5c\u7528\u57df\u7684\u53d8\u91cf i\uff0c\u8fd9\u5c31\u5bfc\u81f4\u5faa\u73af\u4e2d\u7ed1\u5b9a\u4e86\u540c\u4e00\u4e2a\u53d8\u91cf i \u3002\u5f53 6 \u6b21\u5012\u8ba1\u65f6\u7ed3\u675f\u540e\uff0c\u5b83\u4eec\u90fd\u4f7f\u7528\u4e86\u6700\u540e\u76f8\u540c\u7684\u503c 6 \u3002<\/p>\n
let \u521b\u5efa\u7684\u662f\u5757\u7ea7\u4f5c\u7528\u57df\u5f53\u7528\u5728\u5faa\u73af\u4e2d\u65f6\uff0c\u4e3a\u6bcf\u6b21\u5faa\u73af\u521b\u5efa\u4e86\u4e00\u4e2a\u7ed1\u5b9a\u3002\u5faa\u73af\u4e2d\u7684\u6bcf\u6b21\u5012\u8ba1\u65f6\u83b7\u5f97\u4e86\u4ece 0 \u5230 5 \u4e0d\u540c\u7684\u503c\u3002<\/p>\n
for (let i = 0; i <= 5; i++) {\n    setTimeout(function () {\n        console.log(i);\n    }, 1000);\n}\n<\/code><\/pre>\n
\u73b0\u5728\u5c06\u4f1a\u6253\u5370\u51fa 0 \u5230 5\uff0c\u82e5\u4f60\u7684\u76ee\u6807\u73af\u5883\u662f ES5 \u4f7f\u7528 IIFE \u52a0\u95ed\u5305\u7684\u65b9\u6cd5\uff0c\u82e5\u76ee\u6807\u662f ES6 \u8bf7\u4f7f\u7528 let \u65b9\u6cd5\u3002<\/p>\n
\u8fd9\u4e5f\u662f Babel \u5728\u5185\u90e8\u628a ES6 \u7684\u4ee3\u7801\u8f6c\u4e3a ES5 \u4f7f\u7528\u7684\u65b9\u6cd5\uff0c\u628a\u4ee5 let \u4e3a\u57fa\u7840\u7684\u4ee3\u7801\u8f6c\u6362\u4e3a\u95ed\u5305\u548c IIFE \u7684\u7ed3\u5408\u4f53\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u539f\u6587\u5730\u5740\uff1ahttps:\/\/dev.to\/bhagatparwinder\/closures-in-ja...<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[249,2,20,3],"tags":[110,111,6],"class_list":["post-1120","post","type-post","status-publish","format-standard","hentry","category-javascript","category-all","category-frontend","category-tech","tag-closure","tag-iife","tag-javascript"],"_links":{"self":[{"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=\/wp\/v2\/posts\/1120","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1120"}],"version-history":[{"count":1,"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=\/wp\/v2\/posts\/1120\/revisions"}],"predecessor-version":[{"id":1121,"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=\/wp\/v2\/posts\/1120\/revisions\/1121"}],"wp:attachment":[{"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1120"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1120"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1120"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}