{"id":5086,"date":"2022-02-21T22:47:51","date_gmt":"2022-02-21T14:47:51","guid":{"rendered":"http:\/\/123.57.164.21\/?p=5086"},"modified":"2022-02-21T22:47:51","modified_gmt":"2022-02-21T14:47:51","slug":"%e4%bb%80%e4%b9%88%e6%98%af-js-%e5%8e%9f%e5%9e%8b%e9%93%be","status":"publish","type":"post","link":"https:\/\/92it.top\/?p=5086","title":{"rendered":"\u4ec0\u4e48\u662f JS \u539f\u578b\u94fe"},"content":{"rendered":"\n<p>\u8f6c\u8f7d\uff1ahttps:\/\/zhuanlan.zhihu.com\/p\/23090041?refer=study-fe<\/p>\n\n\n\n<p>\u6211\u4eec\u77e5\u9053 JS \u6709\u5bf9\u8c61\uff0c\u6bd4\u5982\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">var obj = { name: 'obj' } \n<\/pre>\n\n\n\n<p>\u6211\u4eec\u53ef\u4ee5\u5bf9 obj \u8fdb\u884c\u4e00\u4e9b\u64cd\u4f5c\uff0c\u5305\u62ec<\/p>\n\n\n\n<ul><li>\u300c\u8bfb\u300d\u5c5e\u6027<\/li><li>\u300c\u65b0\u589e\u300d\u5c5e\u6027<\/li><li>\u300c\u66f4\u65b0\u300d\u5c5e\u6027<\/li><li>\u300c\u5220\u9664\u300d\u5c5e\u6027<\/li><\/ul>\n\n\n\n<p>\u4e0b\u9762\u6211\u4eec\u4e3b\u8981\u6765\u770b\u4e00\u4e0b\u300c\u8bfb\u300d\u548c\u300c\u65b0\u589e\u300d\u5c5e\u6027\u3002<\/p>\n\n\n\n<p><strong>\u4e3a\u4ec0\u4e48\u6709 valueOf \/ toString \u5c5e\u6027\u5462\uff1f<\/strong><\/p>\n\n\n\n<p>\u5728\u6211\u4eec\u6ca1\u6709\u5bf9 obj \u8fdb\u884c\u4efb\u4f55\u5176\u4ed6\u64cd\u4f5c\u4e4b\u524d\uff0c\u53d1\u73b0 obj \u5df2\u7ecf\u6709\u51e0\u4e2a\u5c5e\u6027\uff08\u65b9\u6cd5\uff09\u4e86\uff1a\u3001<\/p>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/123.57.164.21\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-32.png\" alt=\"\" class=\"wp-image-5087\" width=\"385\" height=\"170\" srcset=\"https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-32.png 504w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-32-300x132.png 300w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-32-230x101.png 230w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-32-350x154.png 350w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-32-480x211.png 480w\" sizes=\"(max-width: 385px) 100vw, 385px\" \/><\/figure><\/div>\n\n\n\n<p><u><strong>\u90a3\u4e48\u95ee\u9898\u6765\u4e86\uff1avalueOf \/ toString \/ constructor \u662f\u600e\u4e48\u6765\uff1f\u6211\u4eec\u5e76\u6ca1\u6709\u7ed9 obj.valueOf \u8d4b\u503c\u5440\u3002<\/strong><\/u><\/p>\n\n\n\n<p>\u8981\u641e\u6e05\u695a valueOf \/ toString \/ constructor \u662f\u600e\u4e48\u6765\u7684\uff0c\u5c31\u8981\u7528\u5230 console.dir \u4e86\u3002<\/p>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/123.57.164.21\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-33.png\" alt=\"\" class=\"wp-image-5088\" width=\"536\" height=\"341\" srcset=\"https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-33.png 818w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-33-300x191.png 300w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-33-768x488.png 768w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-33-230x146.png 230w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-33-350x222.png 350w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-33-480x305.png 480w\" sizes=\"(max-width: 536px) 100vw, 536px\" \/><\/figure><\/div>\n\n\n\n<p>\u4e0a\u9762\u8fd9\u4e2a\u56fe\u6709\u70b9\u96be\u61c2\uff0c\u6211\u624b\u753b\u4e00\u4e2a\u793a\u610f\u56fe\uff1a<\/p>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"aligncenter size-large is-resized\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/123.57.164.21\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-34-1024x746.png\" alt=\"\" class=\"wp-image-5089\" width=\"505\" height=\"367\" srcset=\"https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-34-1024x746.png 1024w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-34-300x218.png 300w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-34-768x559.png 768w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-34-830x605.png 830w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-34-550x400.png 550w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-34-230x168.png 230w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-34-350x255.png 350w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-34-480x350.png 480w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-34.png 1384w\" sizes=\"(max-width: 505px) 100vw, 505px\" \/><\/figure><\/div>\n\n\n\n<p>\u6211\u4eec\u53d1\u73b0 console.dir(obj) \u6253\u51fa\u6765\u7684\u7ed3\u679c\u662f\uff1a<\/p>\n\n\n\n<ul><li>1. obj \u672c\u8eab\u6709\u4e00\u4e2a\u5c5e\u6027 name\uff08\u8fd9\u662f\u6211\u4eec\u7ed9\u5b83\u52a0\u7684\uff09<\/li><li>2. obj \u8fd8\u6709\u4e00\u4e2a\u5c5e\u6027\u53eb\u505a __proto__\uff08\u5b83\u662f\u4e00\u4e2a\u5bf9\u8c61\uff09<\/li><li>3. obj.__proto__ \u6709\u5f88\u591a\u5c5e\u6027\uff0c\u5305\u62ec valueOf\u3001toString\u3001constructor \u7b49<\/li><li>4. obj.__proto__ \u5176\u5b9e\u4e5f\u6709\u4e00\u4e2a\u53eb\u505a __proto__ \u7684\u5c5e\u6027\uff08console.log \u6ca1\u6709\u663e\u793a\uff09\uff0c\u503c\u4e3a null<\/li><\/ul>\n\n\n\n<p>\u73b0\u5728\u56de\u5230\u6211\u4eec\u7684\u95ee\u9898\uff1aobj \u4e3a\u4ec0\u4e48\u4f1a\u62e5\u6709 valueOf \/ toString \/ constructor \u8fd9\u51e0\u4e2a\u5c5e\u6027\uff1f<\/p>\n\n\n\n<p>\u7b54\u6848\uff1a<\/p>\n\n\n\n<p>\u8fd9\u8ddf __proto__ \u6709\u5173\u3002<\/p>\n\n\n\n<p>\u5f53\u6211\u4eec\u300c\u8bfb\u53d6\u300d obj.toString \u65f6\uff0cJS \u5f15\u64ce\u4f1a\u505a\u4e0b\u9762\u7684\u4e8b\u60c5\uff1a<\/p>\n\n\n\n<ul><li>1. \u770b\u770b obj \u5bf9\u8c61\u672c\u8eab\u6709\u6ca1\u6709 toString \u5c5e\u6027\u3002\u6ca1\u6709\u5c31\u8d70\u5230\u4e0b\u4e00\u6b65\u3002<\/li><\/ul>\n\n\n\n<ul><li>2. \u770b\u770b obj.__proto__ \u5bf9\u8c61\u6709\u6ca1\u6709 toString \u5c5e\u6027\uff0c\u53d1\u73b0 obj.__proto__ \u6709 toString \u5c5e\u6027\uff0c\u4e8e\u662f\u627e\u5230\u4e86<\/li><\/ul>\n\n\n\n<p>\u6240\u4ee5 obj.toString \u5b9e\u9645\u4e0a\u5c31\u662f\u7b2c 2 \u6b65\u4e2d\u627e\u5230\u7684 obj.__proto__.toString\u3002<\/p>\n\n\n\n<ul><li>3. \u5982\u679c obj.__proto__ \u6ca1\u6709\uff0c\u90a3\u4e48\u6d4f\u89c8\u5668\u4f1a\u7ee7\u7eed\u67e5\u770b obj.__proto__.__proto__<\/li><li>4. \u5982\u679c obj.__proto__.__proto__ \u4e5f\u6ca1\u6709\uff0c\u90a3\u4e48\u6d4f\u89c8\u5668\u4f1a\u7ee7\u7eed\u67e5\u770b obj.__proto__.__proto__.proto__<\/li><\/ul>\n\n\n\n<ul><li>5. \u76f4\u5230\u627e\u5230 toString \u6216\u8005 __proto__ \u4e3a null\u3002<\/li><\/ul>\n\n\n\n<p>\u4e0a\u9762\u7684\u8fc7\u7a0b\uff0c\u5c31\u662f\u300c\u8bfb\u300d\u5c5e\u6027\u7684\u300c\u641c\u7d22\u8fc7\u7a0b\u300d\u3002<\/p>\n\n\n\n<p>\u800c\u8fd9\u4e2a\u300c\u641c\u7d22\u8fc7\u7a0b\u300d\uff0c\u662f\u8fde\u7740\u7531 __proto__ \u7ec4\u6210\u7684\u94fe\u5b50\u4e00\u76f4\u8d70\u7684\u3002<\/p>\n\n\n\n<p><strong><u>\u8fd9\u4e2a\u94fe\u5b50\uff0c\u5c31\u53eb\u505a\u300c\u539f\u578b\u94fe\u300d\u3002<\/u><\/strong><\/p>\n\n\n\n<p><\/p>\n\n\n\n<p><strong>\u5171\u4eab\u539f\u578b\u94fe<\/strong><\/p>\n\n\n\n<p>\u73b0\u5728\u6211\u4eec\u6709\u53e6\u4e00\u4e2a\u5bf9\u8c61<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">var obj2 = { name: 'obj2' }\n<\/pre>\n\n\n\n<p>\u5982\u56fe\uff1a<\/p>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"aligncenter size-large is-resized\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/123.57.164.21\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-35-1024x733.png\" alt=\"\" class=\"wp-image-5091\" width=\"561\" height=\"401\" srcset=\"https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-35-1024x733.png 1024w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-35-300x215.png 300w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-35-768x550.png 768w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-35-830x594.png 830w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-35-230x165.png 230w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-35-350x251.png 350w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-35-480x344.png 480w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-35.png 1374w\" sizes=\"(max-width: 561px) 100vw, 561px\" \/><\/figure><\/div>\n\n\n\n<p>\u90a3\u4e48 obj.toString \u548c obj2.toString \u5176\u5b9e\u662f\u540c\u4e00\u4e2a\u4e1c\u897f\uff0c\u4e5f\u5c31\u662f obj2.__proto__.toString\u3002<\/p>\n\n\n\n<p>\u8fd9\u6709\u4ec0\u4e48\u610f\u4e49\u5462\uff1f<\/p>\n\n\n\n<p>\u5982\u679c\u6211\u4eec\u6539\u5199 obj2.__proto__.toString\uff0c\u90a3\u4e48 obj.toString \u5176\u5b9e\u4e5f\u4f1a\u53d8\uff01<\/p>\n\n\n\n<p>\u8fd9\u6837 obj \u548c obj2 \u5c31\u662f\u5177\u6709\u67d0\u4e9b\u76f8\u540c\u884c\u4e3a\u7684\u5bf9\u8c61\uff0c\u8fd9\u5c31\u662f\u610f\u4e49\u6240\u5728\u3002<\/p>\n\n\n\n<p><\/p>\n\n\n\n<p><strong>\u5dee\u5f02\u5316<\/strong><\/p>\n\n\n\n<p>\u5982\u679c\u6211\u4eec\u60f3\u8ba9 obj.toString \u548c obj2.toString \u7684\u884c\u4e3a\u4e0d\u540c\u600e\u4e48\u505a\u5462\uff1f<\/p>\n\n\n\n<p>\u76f4\u63a5\u8d4b\u503c\u5c31\u597d\u4e86\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">obj.toString = function(){ return '\u65b0\u7684 toString \u65b9\u6cd5' }\n<\/pre>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"aligncenter size-large is-resized\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/123.57.164.21\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-36-1024x757.png\" alt=\"\" class=\"wp-image-5092\" width=\"583\" height=\"430\" srcset=\"https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-36-1024x757.png 1024w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-36-300x222.png 300w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-36-768x568.png 768w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-36-830x614.png 830w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-36-230x170.png 230w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-36-350x259.png 350w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-36-480x355.png 480w, https:\/\/92it.top\/wp-content\/uploads\/2022\/02\/\u56fe\u7247-36.png 1358w\" sizes=\"(max-width: 583px) 100vw, 583px\" \/><\/figure><\/div>\n\n\n\n<p>\u603b\u7ed3\uff1a<\/p>\n\n\n\n<p>\u300c\u8bfb\u300d\u5c5e\u6027\u65f6\u4f1a<strong><u>\u6cbf\u7740\u539f\u578b\u94fe\u641c\u7d22<\/u><\/strong>\u3002<\/p>\n\n\n\n<p>\u300c\u65b0\u589e\u300d\u5c5e\u6027\u65f6<strong><u>\u4e0d\u4f1a<\/u><\/strong>\u53bb\u770b\u539f\u578b\u94fe\uff08\u4f46\u662f\u5982\u679c\u4f60\u7ed9\u8fd9\u4e2a\u5c5e\u6027\u52a0\u4e86\u4e00\u4e9b\u914d\u7f6e\uff0c\u5219\u4e0d\u4e00\u6837\uff0c\u4ee5\u540e\u8bb2\uff09\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u8f6c\u8f7d\uff1ahttps:\/\/zhuanlan.zhihu.com\/p\/23090041?refer=study-fe [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[24],"tags":[],"_links":{"self":[{"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/posts\/5086"}],"collection":[{"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/92it.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5086"}],"version-history":[{"count":2,"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/posts\/5086\/revisions"}],"predecessor-version":[{"id":5093,"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/posts\/5086\/revisions\/5093"}],"wp:attachment":[{"href":"https:\/\/92it.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5086"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/92it.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5086"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/92it.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5086"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}