{"id":259,"date":"2018-12-12T23:59:32","date_gmt":"2018-12-12T15:59:32","guid":{"rendered":"https:\/\/wp.winter-weng.cc\/work\/?p=259"},"modified":"2018-12-12T23:59:32","modified_gmt":"2018-12-12T15:59:32","slug":"ch-3-%e5%87%bd%e5%bc%8f-vs-%e5%8d%80%e5%a1%8a%e7%af%84%e7%96%87","status":"publish","type":"post","link":"https:\/\/wp.winter-weng.cc\/work\/?p=259","title":{"rendered":"Ch. 3 \u51fd\u5f0f vs. \u5340\u584a\u7bc4\u7587"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_75 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"\u986f\u793a\/\u96b1\u85cf\u5167\u5bb9\u76ee\u9304\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#%E6%BA%90%E8%87%AA%E5%87%BD%E5%BC%8F%E7%9A%84%E7%AF%84%E7%96%87\" >\u6e90\u81ea\u51fd\u5f0f\u7684\u7bc4\u7587<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#%E9%9A%B1%E8%97%8F%E5%9C%A8%E6%99%AE%E9%80%9A%E7%AF%84%E7%96%87%E4%B8%AD\" >\u96b1\u85cf\u5728\u666e\u901a\u7bc4\u7587\u4e2d<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#%E9%81%BF%E5%85%8D%E8%A1%9D%E7%AA%81\" >\u907f\u514d\u885d\u7a81<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#%E5%87%BD%E5%BC%8F%E4%BD%9C%E7%82%BA%E7%AF%84%E7%96%87\" >\u51fd\u5f0f\u4f5c\u70ba\u7bc4\u7587<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#%E5%87%BD%E5%BC%8F%E5%AE%A3%E5%91%8A_vs_%E5%87%BD%E5%BC%8F%E9%81%8B%E7%AE%97%E5%BC%8F\" >\u51fd\u5f0f\u5ba3\u544a vs. \u51fd\u5f0f\u904b\u7b97\u5f0f<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#%E5%8C%BF%E5%90%8D_vs_%E5%85%B7%E5%90%8D\" >\u533f\u540d vs. \u5177\u540d<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#%E5%8D%B3%E5%88%BB%E8%AA%BF%E7%94%A8%E5%87%BD%E5%BC%8F%E9%81%8B%E7%AE%97%E5%BC%8F_IIFE\" >\u5373\u523b\u8abf\u7528\u51fd\u5f0f\u904b\u7b97\u5f0f (IIFE)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#%E5%8D%80%E5%A1%8A%E4%BD%9C%E7%82%BA%E7%AF%84%E7%96%87\" >\u5340\u584a\u4f5c\u70ba\u7bc4\u7587<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#with\" >with<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#trycatch\" >try\/catch<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#let\" >let<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#%E5%9E%83%E5%9C%BE%E5%9B%9E%E6%94%B6\" >\u5783\u573e\u56de\u6536<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#let_%E8%BF%B4%E5%9C%88\" >let \u8ff4\u5708<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#const\" >const<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#%E8%A4%87%E7%BF%92\" >\u8907\u7fd2<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"https:\/\/wp.winter-weng.cc\/work\/?p=259\/#%E9%99%84%E9%8C%84_B\" >\u9644\u9304 B<\/a><\/li><\/ul><\/nav><\/div>\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E6%BA%90%E8%87%AA%E5%87%BD%E5%BC%8F%E7%9A%84%E7%AF%84%E7%96%87\"><\/span><strong>\u6e90\u81ea\u51fd\u5f0f\u7684\u7bc4\u7587<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<p>JS \u5177\u6709\u4ee5\u51fd\u5f0f\u70ba\u57fa\u790e\u7684\u7bc4\u7587\u3002\u5176\u5167\u7684\u8b58\u5225\u5b57\u53ea\u80fd\u5728\u51fd\u5f0f\u7684\u7bc4\u7587\u5167\u88ab\u53d6\u7528\u3002<\/p>\n\n\n<hr class=\"wp-block-separator\" \/>\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E9%9A%B1%E8%97%8F%E5%9C%A8%E6%99%AE%E9%80%9A%E7%AF%84%E7%96%87%E4%B8%AD\"><\/span><strong>\u96b1\u85cf\u5728\u666e\u901a\u7bc4\u7587\u4e2d<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<p>\u51fd\u5f0f\u7684\u76f8\u53cd\u601d\u7dad\uff1a\u7576\u628a\u7a0b\u5f0f\u78bc\u6216\u8b8a\u6578\u653e\u5728\u51fd\u5f0f\u4e2d\uff0c\u5176\u6548\u7528\u7b49\u65bc\u300c\u96b1\u85cf\u300d\u4e86\u7a0b\u5f0f\u78bc\u3002<\/p>\n\n\n<p class=\"has-text-color has-vivid-red-color\">\u6700\u5c0f\u6b0a\u9650\u539f\u5247 (principle of least privilege) \/ \u6700\u5c0f\u6388\u6b0a (least authority) \/ \u6700\u5c0f\u66b4\u9732 (least exposure)\uff1a\u5728\u6a21\u7d44\u6216\u7269\u4ef6 API \u4e2d\uff0c\u61c9\u8a72\u53ea\u66b4\u9732\u6700\u5c11\u7684\u6771\u897f\u3002<\/p>\n\n\n<p>\u53c3\u8003 P.31 \u7a0b\u5f0f\u78bc\uff0c\u79c1\u6709\u8b8a\u6578\u6216\u51fd\u5f0f\u7b49\u7d30\u7bc0\uff0c\u61c9\u88ab\u96b1\u85cf\u8d77\u4f86\uff0c\u4ee5\u907f\u514d\u975e\u9810\u671f\u7684\u4f7f\u7528\u3002<\/p>\n\n\n<p style=\"background-color:#fbdee6\" class=\"has-background\">\u4f60\u6703\u96b1\u85cf\u55ce\uff1f\u6216\u662f\u89ba\u5f97\u4ec0\u9ebc\u60c5\u6cc1\u53ef\u4ee5\u96b1\u85cf\uff0c\u8acb\u8209\u51fa\u4e00\u4e9b\u4f8b\u5b50\u3002<\/p>\n\n\n<hr class=\"wp-block-separator\" \/>\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E9%81%BF%E5%85%8D%E8%A1%9D%E7%AA%81\"><\/span>\u907f\u514d\u885d\u7a81<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<p>\u96b1\u85cf\u53ef\u4ee5\u907f\u514d\u540c\u540d\u4f46\u7528\u9014\u4e0d\u540c\u7684\u8b58\u5225\u5b57\u7522\u751f\u885d\u7a81\u6216\u8907\u5beb\u3002<\/p>\n\n\n<p><strong>\u5168\u57df\u547d\u540d\u7a7a\u9593<\/strong><\/p>\n\n\n<p>\u8f09\u5165\u7684\u7a0b\u5f0f\u5eab\u5982\u679c\u6c92\u6709\u96b1\u85cf\u79c1\u6709\u51fd\u5f0f\u3001\u8b8a\u6578\uff0c\u5bb9\u6613\u6c59\u67d3\u5168\u57df\u7a7a\u9593\uff0c\u5f7c\u6b64\u767c\u751f\u885d\u7a81\u3002<\/p>\n\n\n<p>\u53ef\u4ee5\u5efa\u7acb\u4e00\u500b\u7269\u4ef6\u4f5c\u70ba\u547d\u540d\u7a7a\u9593\u4f86\u4f7f\u7528\uff0c\u5c07\u5c0d\u5916\u7684\u51fd\u5f0f\u6216\u8b8a\u6578\u8a2d\u5b9a\u70ba\u8a72\u7269\u4ef6\u7684\u5c6c\u6027\u3002<\/p>\n\n\n<p><strong>\u6a21\u7d44\u7ba1\u7406<\/strong><\/p>\n\n\n<p>\u53e6\u4e00\u500b\u65b9\u6cd5\u662f\u4f7f\u7528\u6a21\u7d44 (module)\uff0c\u85c9\u7531\u5de5\u5177\u7522\u751f\u76f8\u4f9d\u6027\u7ba1\u7406\uff0c\u4e0d\u65b0\u589e\u8b58\u5225\u5b57\u5230\u5168\u57df\u7bc4\u7587\u3002<\/p>\n\n\n<p>\u6a21\u7d44\u7ba1\u7406\u6a5f\u5236\u4e26\u6c92\u6709\u9003\u96e2\u7bc4\u7587\u898f\u5247\u7684\u638c\u63a7\uff0c\u800c\u662f\u5229\u7528\u898f\u5247\u5c07\u8b58\u5225\u5b57\u653e\u7f6e\u65bc\u79c1\u6709\u7684\u3001\u4e0d\u6613\u767c\u751f\u885d\u7a81\u7684\u7bc4\u7587\u4e2d\u3002<\/p>\n\n\n<hr class=\"wp-block-separator\" \/>\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%87%BD%E5%BC%8F%E4%BD%9C%E7%82%BA%E7%AF%84%E7%96%87\"><\/span><strong>\u51fd\u5f0f\u4f5c\u70ba\u7bc4\u7587<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<p>\u5305\u5728\u51fd\u5f0f\u4e2d\u7684\u78ba\u80fd\u5920\u96b1\u85cf\u88e1\u9762\u7684\u7d30\u7bc0\uff0c\u4f46\u6709\u4e00\u4e9b\u554f\u984c\uff1a<\/p>\n\n\n<ul class=\"wp-block-list\"><li>\u5fc5\u9808\u5ba3\u544a\u4e00\u500b\u51fd\u5f0f\u540d\u7a31\uff0c\u5982 <code>foo<\/code>\u3002<\/li><li>\u8981\u660e\u78ba\u5730\u547c\u53eb\u51fd\u5f0f\u624d\u80fd\u5920\u57f7\u884c\u3002<\/li><\/ul>\n\n\n<p>JS \u91dd\u5c0d\u9019\u5169\u500b\u554f\u984c\u63d0\u4f9b\u4e86\u89e3\u6cd5\uff1aIIFE\u3002<\/p>\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%87%BD%E5%BC%8F%E5%AE%A3%E5%91%8A_vs_%E5%87%BD%E5%BC%8F%E9%81%8B%E7%AE%97%E5%BC%8F\"><\/span>\u51fd\u5f0f\u5ba3\u544a vs. \u51fd\u5f0f\u904b\u7b97\u5f0f<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<p>\u51fd\u5f0f\u5ba3\u544a\uff1a\u5229\u7528 <code>function<\/code> \u70ba\u95dc\u9375\u5b57\u4f86\u5ba3\u544a\u3002<\/p>\n\n\n<p>\u51fd\u5f0f\u904b\u7b97\u5f0f\uff1a\u5c07\u51fd\u5f0f\u6307\u5b9a\u7d66\u7279\u5b9a\u8b8a\u6578\uff0c\u5982 <code>var foo = function () { ... }<\/code> \u6216 <code>(function foo() { ... })();<\/code>\u3002<\/p>\n\n\n<p><code>(function foo() { ... })<\/code> \u4ee3\u8868 foo \u53ea\u80fd\u5728 &#8230; \u6240\u6a19\u793a\u7684\u7bc4\u7587\u4e2d\u6240\u627e\u5230\uff0c\u4e0d\u6703\u6c59\u67d3\u5305\u542b\u5b83\u7684\u7bc4\u7587\u3002<\/p>\n\n\n<p style=\"background-color:#fbdee6\" class=\"has-background\">\u8003\u616e\u4ee5\u4e0b\u5169\u500b\u51fd\u5f0f\u904b\u7b97\u5f0f\u3002<\/p>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"true\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">var foo = function(){\n\tconsole.log(foo);\n}\n(function foo(){\n\tconsole.log(foo);\n})()\n<\/pre>\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8C%BF%E5%90%8D_vs_%E5%85%B7%E5%90%8D\"><\/span>\u533f\u540d vs. \u5177\u540d<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<p>\u51fd\u5f0f\u904b\u7b97\u5f0f\u53ef\u4ee5\u662f\u533f\u540d\u7684\u3002\u7f3a\u9ede\uff1a<\/p>\n\n\n<ul class=\"wp-block-list\"><li>\u9664\u932f\u56f0\u96e3\uff1a\u5728\u5806\u758a\u4e2d\u6c92\u6709\u540d\u7a31\u3002<\/li><li>\u8981\u4f7f\u7528\u6642\u53ef\u80fd\u88ab\u68c4\u7528\uff1a\u9700\u8981\u53c3\u8003\u6216\u905e\u8ff4\u6642\uff0c\u6216\u662f\u8981\u89e3\u9664\u4e8b\u4ef6\u7e6b\u7d50 (unbind event) \u7684\u6642\u5019\u3002<\/li><li>\u53ef\u8b80\u6027\u964d\u4f4e\uff1a\u53ef\u8b58\u5225\u7684\u540d\u7a31\u80fd\u8b93\u7a0b\u5f0f\u78bc\u8f03\u5bb9\u6613\u7406\u89e3\u3002<\/li><\/ul>\n\n\n<p class=\"has-text-color has-vivid-red-color\">\u6700\u4f73\u7684\u5be6\u52d9\u505a\u6cd5\u662f\u6c38\u9060\u8b93\u51fd\u5f0f\u904b\u7b97\u5f0f\u5e36\u6709\u81ea\u5df1\u7684\u540d\u7a31\u3002<\/p>\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8D%B3%E5%88%BB%E8%AA%BF%E7%94%A8%E5%87%BD%E5%BC%8F%E9%81%8B%E7%AE%97%E5%BC%8F_IIFE\"><\/span>\u5373\u523b\u8abf\u7528\u51fd\u5f0f\u904b\u7b97\u5f0f (IIFE)<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<p>IIFE \u662f\u53ef\u7acb\u5373\u57f7\u884c\u7684\u51fd\u5f0f\u904b\u7b97\u5f0f\uff0c\u4e0d\u6703\u6c59\u67d3\u5230\u5168\u57df\u7bc4\u570d\uff0c\u4e26\u4e14\u533f\u540d\u6216\u5177\u540d\u7686\u5408\u6cd5\u3002<\/p>\n\n\n<p>\u5404\u7a2e\u8b8a\u9ad4 (P.37)\uff1a<\/p>\n\n\n<ul class=\"wp-block-list\"><li>\u5c07 window \u91cd\u65b0\u6307\u540d\u70ba global\u3002<\/li><li>\u78ba\u4fdd undefined \u6b63\u78ba\u6027\u3002<\/li><li>\u53cd\u8f49\u9806\u5e8f\uff0c\u4e0d\u50b3\u8b8a\u6578\u800c\u662f\u50b3\u51fd\u5f0f\u3002<\/li><\/ul>\n\n\n<hr class=\"wp-block-separator\" \/>\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8D%80%E5%A1%8A%E4%BD%9C%E7%82%BA%E7%AF%84%E7%96%87\"><\/span><strong>\u5340\u584a\u4f5c\u70ba\u7bc4\u7587<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<p>\u76e1\u53ef\u80fd\u5728\u6700\u8fd1\u7684\u5730\u65b9\u5ba3\u544a\u8b8a\u6578\u3002<\/p>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"true\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">for (var i = 0; i&lt;10; i++) {\n\tconsole.log(i);\n}\nconsole.log(i);\n<\/pre>\n\n\n<p>\u4f8b\u5982\u9810\u671f i \u53ea\u5728 for \u4e2d\u88ab\u4f7f\u7528\uff0c\u4f46\u9019\u4e26\u4e0d\u662f\u771f\u6b63\u7684\u5340\u584a\u7bc4\u7587\uff0c\u800c\u662f\u4ef0\u8cf4\u98a8\u683c\u548c\u81ea\u6211\u7d04\u675f\u507d\u9020\u51fa\u4f86\u7684\u7bc4\u7587\u3002<\/p>\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"with\"><\/span>with<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<p>with \u900f\u904e\u7269\u4ef6\u5efa\u7acb\u51fa\u4f86\u7684\u7bc4\u7587\uff0c\u5be6\u969b\u4e0a\u662f\u4e00\u7a2e\u5340\u584a\u7bc4\u7587\u7684\u5be6\u4f8b\u3002\u9019\u500b\u7bc4\u7587\u53ea\u6703\u5728 with \u7684\u751f\u547d\u9031\u671f\u4e2d\u5b58\u5728\uff0c\u800c\u4e14\u4e0d\u5728\u5305\u542b\u5b83\u7684\u7bc4\u7587\u4e2d\u3002<\/p>\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"trycatch\"><\/span>try\/catch<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<p>\u5728 try\/catch \u4e2d\u7684\u8b8a\u6578\u5ba3\u544a\uff0c\u6703\u4ee5 catch \u5340\u584a\u70ba\u7bc4\u7587\u3002<\/p>\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"let\"><\/span>let<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<p>ES6 \u6539\u8b8a\u4e16\u754c\uff5e<\/p>\n\n\n<p>let \u6703\u96b1\u542b\u5730\u5c07\u8b8a\u6578\u5ba3\u544a\u63a5\u9644\u5230\u5b83\u6240\u5728\u7684\u5340\u584a (\u901a\u5e38\u662f\u4e00\u5c0d { &#8230; })\u3002<\/p>\n\n\n<p>\u53ef\u4ee5\u5728\u7a0b\u5f0f\u78bc\u4e2d\u653e\u5165\u660e\u78ba\u7684\u4e00\u5c0d { &#8230; } \uff0c\u4ee5\u88fd\u4f5c\u4e00\u500b\u660e\u78ba\u7684\u5340\u584a\u3002<\/p>\n\n\n<p><span class=\"has-text-color has-vivid-red-color\">let \u4e0d\u6703\u88ab\u62c9\u5347\u3002<\/span><\/p>\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%9E%83%E5%9C%BE%E5%9B%9E%E6%94%B6\"><\/span>\u5783\u573e\u56de\u6536<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<p>\u5ba3\u544a\u660e\u78ba\u7684\u5340\u584a\uff0c\u53ef\u4ee5\u5411 Engine \u6e05\u695a\u5730\u8868\u793a\u7bc4\u570d\u4e2d\u7684\u8b58\u5225\u5b57\u4e0d\u9700\u8981\u518d\u88ab\u4fdd\u7559\u4e86\u3002(\u53c3\u8003 P.43)<\/p>\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"let_%E8%BF%B4%E5%9C%88\"><\/span>let \u8ff4\u5708<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"true\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">for (let i = 0; i &lt; 10; i++) {\n\tconsole.log(i);\n}\nconsole.log(i); \/\/ ReferenceError\n<\/pre>\n\n\n<p>\u5728 for \u8ff4\u5708\u4e2d\u4f7f\u7528\uff0c\u4e0d\u53ea\u5c07 i \u9650\u5236\u65bc for \u7684\u5340\u584a\u7bc4\u7587\u4e2d\uff0c\u9084\u6703\u6bcf\u6b21\u90fd\u91cd\u65b0\u7d81\u5b9a (rebind)\uff0c\u5c07\u524d\u4e00\u6b21\u8fed\u4ee3\u7684\u7d50\u679c\u91cd\u65b0\u8ce6\u503c\u3002<\/p>\n\n\n<p>\u5982\u679c\u73fe\u6709\u7a0b\u5f0f\u78bc\u5c0d\u8b8a\u6578\u5ba3\u544a\u6709\u7bc4\u7587\u4f9d\u8cf4\u6027\uff0c\u91cd\u69cb\u6216\u79fb\u52d5\u6642\u8981\u7279\u5225\u6ce8\u610f (\u53c3\u8003 P.45)\u3002<\/p>\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"const\"><\/span>const<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<p>\u8207 let \u96f7\u540c\uff0c\u4f46\u5176\u503c\u662f\u56fa\u5b9a\u4e0d\u53ef\u8b8a\u7684\u3002\u5617\u8a66\u6539\u8b8a\u6703\u6709 ReferenceError\u3002<\/p>\n\n\n<hr class=\"wp-block-separator\" \/>\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%A4%87%E7%BF%92\"><\/span><strong>\u8907\u7fd2<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<ul class=\"wp-block-list\"><li>\u5ba3\u544a\u5728\u51fd\u5f0f\u5167\u7684\u8b58\u5225\u5b57\u6703\u88ab\u96b1\u85cf\u8d77\u4f86\u3002<\/li><li>\u9664\u4e86\u51fd\u5f0f\u7bc4\u7587\uff0c\u4e5f\u6709\u5340\u584a\u7bc4\u7587 (ES3 catch\u3001ES6 let, const)\u3002<\/li><\/ul>\n\n\n<hr class=\"wp-block-separator\" \/>\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E9%99%84%E9%8C%84_B\"><\/span><strong>\u9644\u9304 B<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n<p>\u4f7f\u7528 try\/catch \u4f86\u9054\u6210\u5340\u584a\u7bc4\u7587\u5be6\u4f5c\u3002<\/p>\n\n\n<p>let \u8ff0\u53e5\uff0c\u900f\u904e let \u8ff0\u53e5\u5efa\u7acb\u4e00\u500b\u660e\u78ba\u7684\u5340\u584a\uff0c\u4e26\u5c07\u5ba3\u544a\u81f3\u65bc\u5340\u584a\u7684\u9802\u7aef\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u6e90\u81ea\u51fd\u5f0f\u7684\u7bc4\u7587 JS \u5177\u6709\u4ee5\u51fd\u5f0f\u70ba\u57fa\u790e\u7684\u7bc4\u7587\u3002\u5176\u5167&hellip;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"pgc_sgb_lightbox_settings":"","footnotes":""},"categories":[13,12],"tags":[21],"class_list":["post-259","post","type-post","status-publish","format-standard","hentry","category-jsclosuresthis","category-12","tag-javascript"],"_links":{"self":[{"href":"https:\/\/wp.winter-weng.cc\/work\/index.php?rest_route=\/wp\/v2\/posts\/259","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wp.winter-weng.cc\/work\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wp.winter-weng.cc\/work\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wp.winter-weng.cc\/work\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/wp.winter-weng.cc\/work\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=259"}],"version-history":[{"count":0,"href":"https:\/\/wp.winter-weng.cc\/work\/index.php?rest_route=\/wp\/v2\/posts\/259\/revisions"}],"wp:attachment":[{"href":"https:\/\/wp.winter-weng.cc\/work\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=259"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wp.winter-weng.cc\/work\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=259"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wp.winter-weng.cc\/work\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=259"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}