{"id":12945,"date":"2023-11-29T10:09:57","date_gmt":"2023-11-29T02:09:57","guid":{"rendered":"https:\/\/wx.kaifamiao.info\/?p=12945"},"modified":"2023-11-29T10:10:02","modified_gmt":"2023-11-29T02:10:02","slug":"qian-duan-mian-shi-ti-shen-me-shi-zuo-yong-yu","status":"publish","type":"post","link":"http:\/\/wx.kaifamiao.info\/index.php\/2023\/11\/29\/qian-duan-mian-shi-ti-shen-me-shi-zuo-yong-yu\/","title":{"rendered":"\u524d\u7aef\u9762\u8bd5\u9898\uff1a\u4ec0\u4e48\u662f\u4f5c\u7528\u57df\uff1f"},"content":{"rendered":"<p>JavaScript\u4e2d\u7684\u4f5c\u7528\u57df\u662f\u6211\u4eec\u53ef\u4ee5\u6709\u6548\u8bbf\u95ee\u53d8\u91cf\u6216\u51fd\u6570\u7684\u533a\u57df\u3002JS\u6709\u4e09\u79cd\u7c7b\u578b\u7684\u4f5c\u7528\u57df\uff1a\u5168 \u5c40\u4f5c\u7528\u57df\u3001\u51fd\u6570\u4f5c\u7528\u57df\u548c\u5757\u4f5c\u7528\u57df(ES6)\u3002<br \/>\n\u5168\u5c40\u4f5c\u7528\u57df\u2014\u2014\u5728\u5168\u5c40\u547d\u540d\u7a7a\u95f4\u4e2d\u58f0\u660e\u7684\u53d8\u91cf\u6216\u51fd\u6570\u4f4d\u4e8e\u5168\u5c40\u4f5c\u7528\u57df\u4e2d\uff0c\u56e0\u6b64\u5728\u4ee3\u7801\u4e2d\u7684\u4efb\u4f55 \u5730\u65b9\u90fd\u53ef\u4ee5\u8bbf\u95ee\u5b83\u4eec\u3002<br \/>\n\/\/global namespace<br \/>\nvar g = &quot;global&quot;\uff1b<br \/>\nfunction globalFunc(){<br \/>\nfunction innerFuncO {<br \/>\nconsole. log(g)\uff1b \/\/ can access &quot;g&quot; because &quot;g&quot; is a global variable<br \/>\n}<br \/>\ninnerFunc ();<br \/>\n}<br \/>\n\u51fd\u6570\u4f5c\u7528\u57df\u2014\u2014\u5728\u51fd\u6570\u4e2d\u58f0\u660e\u7684\u53d8\u91cf\u3001\u51fd\u6570\u548c\u53c2\u6570\u53ef\u4ee5\u5728\u51fd\u6570\u5185\u90e8\u8bbf\u95ee\uff0c\u4f46\u4e0d\u80fd\u5728\u51fd\u6570\u5916\u90e8\u8bbf \u95ee\u3002<br \/>\nfunction myFavoriteFunc(a) {<br \/>\nif (true) {<br \/>\nvar b = &quot;Hello &quot; + a\uff1b<br \/>\n}<br \/>\nreturn b\uff1b<br \/>\n}<br \/>\nmyFavoriteFunc(&quot;World&quot;)\uff1b<br \/>\nconsole. log(a)\uff1b \/\/ Throws a ReferenceError &quot;a&quot; is not defined console. log(b)\uff1b \/\/ does not continue here<br \/>\n\u5757\u4f5c\u7528\u57df-\u5728\u5757{}\u4e2d\u58f0\u660e\u7684\u53d8\u91cf(let, const)\u53ea\u80fd\u5728\u5176\u4e2d\u8bbf\u95ee\u3002<br \/>\nfunction testBlock() {<br \/>\nif(true){<br \/>\nlet z = 5\uff1b<br \/>\n}<br \/>\nreturn z\uff1b<br \/>\n}<br \/>\ntestBlock()\uff1b \/\/ Throws a ReferenceError &quot;z&quot; is not defined<br \/>\n\u4f5c\u7528\u57df\u4e5f\u662f\u4e00\u7ec4\u7528\u4e8e\u67e5\u627e\u53d8\u91cf\u7684\u89c4\u5219\u3002\u5982\u679c\u53d8\u91cf\u5728\u5f53\u524d\u4f5c\u7528\u57df\u4e2d\u4e0d\u5b58\u5728\uff0c\u5b83\u5c06\u5411\u5916\u90e8\u4f5c\u7528\u57df\u4e2d \u67e5\u627e\u5e76\u635c\u7d22\uff0c\u5982\u679c\u8be5\u53d8\u91cf\u4e0d\u5b58\u5728\uff0c\u5b83\u5c06\u518d\u6b21\u67e5\u627e\u76f4\u5230\u5230\u8fbe\u5168\u5c40\u4f5c\u7528\u57df\uff0c\u5982\u679c\u627e\u5230\uff0c\u5219\u53ef\u4ee5\u4f7f\u7528 \u5b83\uff0c\u5426\u5219\u5f15\u53d1\u9519\u8bef\uff0c\u8fd9\u79cd\u67e5\u627e\u8fc7\u7a0b\u4e5f\u79f0\u4e3a\u4f5c\u7528\u57df\u94fe\u3002<br \/>\n\/*\u4f5c\u7528\u57df\u94fe<br \/>\n\u5185\u90e8\u4f5c\u7528\u57df-\u3009\u5916\u90e8\u4f5c\u7528\u57df-&gt; \u5168\u5c40\u4f5c\u7528\u57df<br \/>\n*\/<br \/>\n\/\/\u5168\u5c40\u4f5c\u7528\u57df<br \/>\nvar variablel = &quot;Comrades&quot;\uff1b<br \/>\nvar variable2 = &quot;Sayonara&quot;\uff1b<br \/>\nfunction outer () {<br \/>\n\/\/\u5916\u90e8\u4f5c\u7528\u57df<br \/>\nvar variablel = &quot;World&quot;\uff1b<br \/>\nfunction inner () {<br \/>\n\/\/\u5185\u90e8\u4f5c\u7528\u57df<br \/>\nvar variable2 = &quot;Hello&quot;\uff1b<br \/>\nconsole. log(variable2 + &quot; &quot; + variablel)\uff1b<br \/>\n}<br \/>\ninner ()\uff1b<br \/>\n}<br \/>\nouter()\uff1b \/\/ Hello World<\/p>\n","protected":false},"excerpt":{"rendered":"<p>JavaScript\u4e2d\u7684\u4f5c\u7528\u57df\u662f\u6211\u4eec\u53ef\u4ee5\u6709\u6548\u8bbf\u95ee\u53d8\u91cf\u6216\u51fd\u6570\u7684\u533a\u57df\u3002JS\u6709\u4e09\u79cd\u7c7b\u578b\u7684\u4f5c\u7528\u57df\uff1a\u5168 \u5c40\u4f5c\u7528\u57df\u3001\u51fd\u6570\u4f5c [&hellip;]<\/p>\n","protected":false},"author":8,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[103],"tags":[],"class_list":["post-12945","post","type-post","status-publish","format-standard","hentry","category-qianduan"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/12945","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/comments?post=12945"}],"version-history":[{"count":1,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/12945\/revisions"}],"predecessor-version":[{"id":12946,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/12945\/revisions\/12946"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=12945"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=12945"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=12945"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}