{"id":593,"date":"2018-01-14T17:58:18","date_gmt":"2018-01-14T09:58:18","guid":{"rendered":"http:\/\/zouyang1230.com\/blog\/?p=593"},"modified":"2020-10-28T22:46:57","modified_gmt":"2020-10-28T14:46:57","slug":"javascript%e6%b7%b1%e5%b1%82%e5%b7%a5%e4%bd%9c%e5%8e%9f%e7%90%86%e8%a7%a3%e6%9e%90%e4%ba%8c%e6%b7%b1%e5%85%a5v8%e5%bc%95%e6%93%8e%e5%a6%82%e4%bd%95%e4%b9%a6%e5%86%99%e6%80%a7%e8%83%bd%e5%bc%ba","status":"publish","type":"post","link":"http:\/\/www.imzouyang.com\/blog\/archives\/593.html","title":{"rendered":"\u5f15\u64ce\u4e0e\u73af\u5883(\u4e8c):\u6df1\u5165V8\u5f15\u64ce+\u5982\u4f55\u4e66\u5199\u6027\u80fd\u5f3a\u52b2\u7684\u4ee3\u7801"},"content":{"rendered":"<p>\u524d\u4e00\u7bc7\u6587\u7ae0<a href=\"http:\/\/zouyang1230.com\/blog\/archives\/547\" rel=\"noopener noreferrer\" target=\"_blank\">JavaScript\u6df1\u5c42\u5de5\u4f5c\u539f\u7406\u89e3\u6790(\u4e00)<\/a>\u4e2d\uff0c\u6211\u4eec\u6982\u89c8\u4e86js\u8fd0\u884c\u7684\u5f15\u64ce\u3001\u8fd0\u884c\u73af\u5883\u3001\u8c03\u7528\u6808\u3002<br \/>\n\u672c\u7bc7\u5c06\u6df1\u5165google\u7684V8\u5f15\u64ce\uff0c\u968f\u540e\u4f1a\u8bb2\u5230\u5982\u4f55\u4e66\u5199\u6027\u80fd\u6700\u4f18\u7684\u4ee3\u7801\u3002\uff08\u60f3\u8981\u76f4\u63a5\u770b\u7ed3\u679c\u7684\u670b\u53cb\u76f4\u63a5\u770b\u6700\u540e\u7684\u6280\u5de7\u5efa\u8bae\u4fbf\u53ef\uff09<\/p>\n<p>&emsp;<\/p>\n<h4>\u4e00\u3001\u6982\u89c8<\/h4>\n<p>\u4e00\u4e2aJavascript\u5f15\u64ce\u5c31\u662f\u4e00\u4e2a\u7a0b\u5e8f\uff08\u4e00\u4e2a\u6267\u884cjs\u4ee3\u7801\u7684<a href=\"https:\/\/baike.baidu.com\/item\/%E8%A7%A3%E9%87%8A%E5%99%A8\/10418965?fr=aladdin\" rel=\"noopener noreferrer\" target=\"_blank\">\u89e3\u91ca\u5668<\/a>\uff09<br \/>\n\u4e0b\u9762\u662f\u4e00\u4e2a\u5b9e\u73b0\u4e86js\u5f15\u64ce\u7684\u9879\u76ee\u5217\u8868\uff1a<\/p>\n<ul>\n<li><a href=\"https:\/\/en.wikipedia.org\/wiki\/V8_%28JavaScript_engine%29\" rel=\"noopener noreferrer\" target=\"_blank\">V8<\/a>\u200a\u2014\u200aGoogle\u5f00\u6e90\u5f15\u64ce\uff0c\u7531C++\u7f16\u5199\uff1b<\/li>\n<li><a href=\"https:\/\/en.wikipedia.org\/wiki\/Rhino_%28JavaScript_engine%29\" rel=\"noopener noreferrer\" target=\"_blank\">Rhino<\/a> \u2014\u200aMozilla\u5f00\u6e90\u5e76\u7ba1\u7406\u7740\uff0c\u7531Java\u7f16\u5199\uff1b<\/li>\n<li><a href=\"https:\/\/en.wikipedia.org\/wiki\/SpiderMonkey\" rel=\"noopener noreferrer\" target=\"_blank\">SpiderMonkey\u200a<\/a> \u2014\u200a\u7b2c\u4e00\u4e2ajs\u5f15\u64ce, \u5728Netscape Navigator\u90a3\u4e2a\u65f6\u4ee3\u7684\u4ea7\u7269\uff1b<\/li>\n<li><a href=\"https:\/\/en.wikipedia.org\/wiki\/JavaScriptCore\" rel=\"noopener noreferrer\" target=\"_blank\">JavaScriptCore<\/a>\u200a\u2014\u200awebkit\u7684\u4e00\u4e2a\u91cd\u8981\u7ec4\u6210\u90e8\u5206\uff0c\u4e3b\u8981\u662f\u5bf9JS\u8fdb\u884c\u89e3\u6790\u548c\u63d0\u4f9b\u6267\u884c\u73af\u5883\uff1b08\u5e74WebKit\u9879\u76ee\u91cd\u5199\u4e86JavaScriptCore\uff0cApple\u5e94\u7528\u5728\u4e86Safari\u4e0a\uff1b<\/li>\n<li><a href=\"https:\/\/en.wikipedia.org\/wiki\/KJS_(software)\" rel=\"noopener noreferrer\" target=\"_blank\">KJS<\/a>\u200a\u2014\u200a<a href=\"https:\/\/en.wikipedia.org\/wiki\/KDE\" rel=\"noopener noreferrer\" target=\"_blank\">KDE<\/a>\u9879\u76ee\u7684Konqueror web\u6d4f\u89c8\u5668\u5f15\u64ce\uff1b<\/li>\n<li><a href=\"https:\/\/en.wikipedia.org\/wiki\/Chakra_%28JScript_engine%29\" rel=\"noopener noreferrer\" target=\"_blank\">Chakra (JScript9)<\/a>\u200a\u2014\u200aInternet Explorer<\/li>\n<li><a href=\"https:\/\/en.wikipedia.org\/wiki\/Chakra_%28JavaScript_engine%29\" rel=\"noopener noreferrer\" target=\"_blank\">Chakra (JavaScript)<\/a>\u200a\u2014\u200aMicrosoft Edge<\/li>\n<li><a href=\"https:\/\/en.wikipedia.org\/wiki\/Nashorn_%28JavaScript_engine%29\" rel=\"noopener noreferrer\" target=\"_blank\">Nashorn<\/a>\u200a\u2014 OpenJDK\u5185\u7684\u5f00\u6e90\u5f15\u64ce\uff0c\u7531Oracle Java Languages and Tool Group\u7f16\u5199\uff1b<\/li>\n<li><a href=\"https:\/\/en.wikipedia.org\/wiki\/JerryScript\" rel=\"noopener noreferrer\" target=\"_blank\">JerryScript<\/a>\u200a\u2014\u200a\u4e00\u4e2a\u4e3a<a href=\"https:\/\/en.wikipedia.org\/wiki\/Internet_of_things\" rel=\"noopener noreferrer\" target=\"_blank\">Internet of Things<\/a>\u800c\u751f\u7684\u5f15\u64ce\u3002<\/li>\n<\/ul>\n<p>&emsp;<\/p>\n<h4>\u4e8c\u3001\u4e3a\u4f55\u521b\u9020V8\u5f15\u64ce<\/h4>\n<p>Google\u7528C++\u7f16\u5199\u521b\u9020\u4e86V8\u5f15\u64ce\u5e76\u5f00\u6e90\uff0c\u5b83\u88ab\u7528\u4e8eChrome\u5185\uff0c\u540c\u65f6\u8fd8\u7528\u4e8eNodejs\u3002<br \/>\nV8\u662f\u7b2c\u4e00\u4e2a\u8bbe\u8ba1\u7528\u6765\u63d0\u9ad8js\u5728web\u6d4f\u89c8\u5668\u7684\u6267\u884c\u6027\u80fd\u7684\u5f15\u64ce\u3002\u4e3a\u4e86\u83b7\u5f97\u66f4\u597d\u7684js\u6267\u884c\u901f\u5ea6\uff0cV8\u5c06JavaScript\u4ee3\u7801\u8f6c\u6362\u4e3a\u66f4\u9ad8\u6548\u7684\u673a\u5668\u4ee3\u7801\uff0c\u800c\u4e0d\u662f\u4f7f\u7528\u89e3\u91ca\u5668\u3002\u5b83\u901a\u8fc7\u5b9e\u73b0\u4e00\u4e2aJIT(\u5373\u65f6)\u7f16\u8bd1\u5668\uff0c\u5c31\u50cf\u8bb8\u591a\u73b0\u4ee3\u7684JavaScript\u5f15\u64ce\u4e00\u6837\uff0c\u50cfSpiderMonkey\u6216Rhino(Mozilla)\u4e00\u6837\uff0c\u5c06JavaScript\u4ee3\u7801\u7f16\u8bd1\u6210\u673a\u5668\u4ee3\u7801\u3002\u8fd9\u91cc\u7684\u4e3b\u8981\u533a\u522b\u662fV8\u6ca1\u6709\u751f\u6210\u5b57\u8282\u7801\u6216\u4efb\u4f55\u4e2d\u95f4\u4ee3\u7801\u3002<\/p>\n<p>&emsp;<\/p>\n<h4>\u4e09\u3001V8\u7684\u7f16\u8bd1\u5668\u53ca\u7ebf\u7a0b<\/h4>\n<p>\u57285.9\u7248\u672c\u4e4b\u524d\uff0cV8\u67092\u4e2a\u7f16\u8bd1\u5668\uff1a<\/p>\n<ul>\n<li>full-codegen\u200a\u2014\u200a\u4e00\u4e2a\u7b80\u5355\u5feb\u901f\u7684\u7f16\u8bd1\u5668\uff0c\u5b83\u4ea7\u51fa\u7b80\u5355\u3001\u76f8\u5bf9\u800c\u8a00\u901f\u5ea6\u7565\u6162\u7684\u673a\u5668\u4ee3\u7801\uff1b<\/li>\n<li>Crankshaft\u200a\u2014\u200a\u4e00\u4e2a\u8fd0\u884c\u65f6\u4f18\u5316\u8fc7\u7684\u7f16\u8bd1\u5668\uff0c\u76f8\u5bf9\u800c\u8a00\u4f1a\u4ea7\u51fa\u66f4\u9ad8\u6548\u7684\u4ee3\u7801\u3002<\/li>\n<\/ul>\n<p>V8\u5f15\u64ce\u5185\u90e8\u5f00\u542f\u4e86\u591a\u7ebf\u7a0b\uff1a<\/p>\n<ul>\n<li>\u4e3b\u7ebf\u7a0b\u8fd0\u884c\u3001\u7f16\u8bd1\u3001\u6267\u884c\u4ee3\u7801\uff1b<\/li>\n<li>\u8fd8\u6709\u4e00\u4e2a\u7528\u4e8e\u7f16\u8bd1\u7684\u5355\u72ec\u7684\u7ebf\u7a0b\uff0c\u4ee5\u4fbf\u4e3b\u7ebf\u7a0b\u53ef\u4ee5\u7ee7\u7eed\u6267\u884c\uff0c\u800c\u524d\u8005\u662f\u5728\u4f18\u5316\u4ee3\u7801\uff1b<\/li>\n<li>\u4e00\u4e2a\u5206\u6790\u5668\u7ebf\u7a0b\uff0c\u5b83\u5c06\u544a\u8bc9\u8fd0\u884c\u65f6\u6211\u4eec\u82b1\u4e86\u5f88\u591a\u65f6\u95f4\uff0c\u4ee5\u4fbfCrankshaft\u4f18\u5316\u5b83\u4eec\uff1b<\/li>\n<li>\u5904\u7406\u5783\u573e\u6536\u96c6\u5668\u6e05\u7406\u7684\u51e0\u4e2a\u7ebf\u7a0b\u3002<\/li>\n<\/ul>\n<p>\u5185\u90e8\u5177\u4f53\u5982\u4f55\u914d\u5408\u7684\uff0c\u5982\u4e0b\uff1a<\/p>\n<p>\u5728\u7b2c\u4e00\u6b21\u6267\u884cJavaScript\u4ee3\u7801\u65f6\uff0cV8\u5229\u7528\u4e86full-codegen\u7f16\u8bd1\u5668\uff0c\u8be5\u4ee3\u7801\u76f4\u63a5\u5c06\u89e3\u6790\u540e\u7684JavaScript\u8f6c\u6362\u4e3a\u673a\u5668\u4ee3\u7801\uff0c\u800c\u65e0\u9700\u8fdb\u884c\u4efb\u4f55\u8f6c\u6362\u3002\u8fd9\u4f7f\u5f97\u5b83\u53ef\u4ee5\u975e\u5e38\u5feb\u5730\u5f00\u59cb\u6267\u884c\u673a\u5668\u4ee3\u7801\u3002\u6ce8\u610f\uff0cV8\u5e76\u6ca1\u6709\u4f7f\u7528\u4e2d\u95f4\u5b57\u8282\u7801\u8868\u793a\uff0c\u8fd9\u6837\u53ef\u4ee5\u6d88\u9664\u5bf9\u89e3\u91ca\u5668\u7684\u9700\u8981\u3002<\/p>\n<p>\u5f53\u60a8\u7684\u4ee3\u7801\u8fd0\u884c\u4e86\u4e00\u6bb5\u65f6\u95f4\u540e\uff0c\u5206\u6790\u5668\u7ebf\u7a0b\u5df2\u7ecf\u6536\u96c6\u4e86\u8db3\u591f\u7684\u6570\u636e\u6765\u5224\u65ad\u5e94\u8be5\u5bf9\u54ea\u4e2a\u65b9\u6cd5\u8fdb\u884c\u4f18\u5316\u3002<\/p>\n<p>\u63a5\u4e0b\u6765\uff0cCrankshaft\u7f16\u8bd1\u5668\u4ece\u53e6\u4e00\u4e2a\u7ebf\u7a0b\u5f00\u59cb\u5bf9\u4ee3\u7801\u8fdb\u884c\u4f18\u5316\u3002\u5927\u591a\u6570\u4f18\u5316\u90fd\u662f\u5728\u8fd9\u4e2a\u7ea7\u522b\u5b8c\u6210\u7684\u3002<\/p>\n<p>&emsp;<\/p>\n<h4>\u56db\u3001\u5173\u8054\u7ec4\u5408\u4ee3\u7801<\/h4>\n<p>\u7b2c\u4e00\u4e2a\u4f18\u5316\u662f\u9884\u5148\u5185\u8054\u5c3d\u53ef\u80fd\u591a\u7684\u4ee3\u7801\u3002\u5185\u8054\u5c31\u662f\u628a\u8c03\u7528\u51fd\u6570\u7684\u5730\u65b9\u66ff\u6362\u6210\u51fd\u6570\u4f53\u4ee3\u7801\u6267\u884c\u7ed3\u679c\u3002\u8fd9\u4e2a\u7b80\u5355\u7684\u6b65\u9aa4\u5141\u8bb8\u4ee5\u4e0b\u7684\u4f18\u5316\u66f4\u6709\u610f\u4e49\u3002<br \/>\n<img loading=\"lazy\" src=\"http:\/\/47.108.172.62\/blog\/wp-content\/uploads\/2018\/01\/0-RRgTDdRfLGEhuR7U-300x279.png\" alt=\"\" width=\"300\" height=\"279\" class=\"aligncenter size-medium wp-image-594\" srcset=\"http:\/\/www.imzouyang.com\/blog\/wp-content\/uploads\/2018\/01\/0-RRgTDdRfLGEhuR7U-300x279.png 300w, http:\/\/www.imzouyang.com\/blog\/wp-content\/uploads\/2018\/01\/0-RRgTDdRfLGEhuR7U.png 512w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/p>\n<p>js\u662f\u4e00\u95e8\u57fa\u4e8e\u539f\u578b\u94fe(prototype)\u7684\u8bed\u8a00\uff0c\u5b83\u4e5f\u662f\u4e00\u95e8\u52a8\u6001\u7f16\u7a0b\u8bed\u8a00\uff0c\u610f\u5473\u7740\u53ef\u4ee5\u5f88\u8f7b\u6613\u7684\u4ece\u4e00\u4e2a\u5b9e\u4f8b\u5316\u7684\u5bf9\u8c61\u4e0a\u6dfb\u52a0\u6216\u8005\u5220\u9664\u5404\u79cd\u5c5e\u6027\u3002<br \/>\n\u5927\u591a\u6570JavaScript\u89e3\u91ca\u5668\u4f7f\u7528\u7c7b\u5b57\u5178\u7684\u7ed3\u6784(\u57fa\u4e8e<a href=\"https:\/\/en.wikipedia.org\/wiki\/Hash_function\" rel=\"noopener noreferrer\" target=\"_blank\">\u54c8\u5e0c\u51fd\u6570<\/a>)\u6765\u5b58\u50a8\u5bf9\u8c61\u5c5e\u6027\u503c\u5728\u5185\u5b58\u4e2d\u7684\u4f4d\u7f6e\u3002\u8fd9\u79cd\u7c7b\u5b57\u5178\u7ed3\u6784\u5728\u68c0\u7d22\u5c5e\u6027\u65f6\u7684\u6027\u80fd\uff0c\u76f8\u8f83\u4e8e\u9759\u6001\u7c7b\u578b\u8bed\u8a00\uff08\u6bd4\u5982Java\u3001C#\uff09\u4f1a\u66f4\u6602\u8d35\uff08\u5f00\u9500\u5927\uff09\u3002\u5728Java\u4e2d\uff0c\u6240\u6709\u5bf9\u8c61\u5c5e\u6027\u90fd\u662f\u5728\u7f16\u8bd1\u4e4b\u524d\u7531\u56fa\u5b9a\u7684\u5bf9\u8c61\u5e03\u5c40\uff08fixed object layout\uff09\u51b3\u5b9a\u7684\uff0c\u5728\u8fd0\u884c\u65f6\u4e0d\u80fd\u52a8\u6001\u6dfb\u52a0\u6216\u5220\u9664\uff0c\u6211\u4eec\u77e5\u9053\uff0c\u5728\u5b58\u50a8\u4e0d\u540c\u7c7b\u578b\u7684\u503c\u7684\u65f6\u5019\u9700\u8981\u5206\u914d\u7684\u5185\u5b58\u5927\u5c0f\u548c\u5730\u5740\u662f\u4e0d\u4e00\u6837\u7684\uff0c\u56e0\u6b64\u4e00\u5f00\u59cb\u5c31\u5b9a\u4e49\u597d\u8be5\u5bf9\u8c61\u5c5e\u6027\u7684\u7c7b\u578b\u662f\u4ec0\u4e48\uff0c\u5c31\u80fd\u5728\u4e00\u5f00\u59cb\u5c31\u786e\u5b9a\u597d\u8be5\u7c7b\u578b\u9700\u8981\u5728\u5185\u5b58\u4e2d\u5360\u636e\u7684\u7a7a\u95f4\u3002<\/p>\n<p>\u63a5\u4e0b\u6765\u8ba9\u6211\u4eec\u770b\u770bV8\u5982\u4f55\u901a\u8fc7\u7c7b\u5b57\u5178\u6765\u5feb\u901f\u7684\u5728\u5185\u5b58\u4e2d\u67e5\u627e\u51fa\u5bf9\u8c61\u7684\u5c5e\u6027\uff1a<\/p>\n<p>\u8fd9\u662f\u4e00\u4e2a\u793a\u4f8b\uff1a<\/p>\n<pre><code class=\"javascript\">\nfunction Point(x, y) {\n    this.x = x;\n    this.y = y;\n}\nvar p1 = new Point(1, 2);\n<\/code><\/pre>\n<p>\u5f53\u201c new Point(1,2) \u201d\u88ab\u8c03\u7528\u65f6\uff0cV8\u5c06\u4f1a\u521b\u5efa\u4e00\u4e2a\u88ab\u79f0\u4e3a\u201cC0\u201d\u7684\u9690\u85cf\u7c7b\uff08hidden class\uff09,C0\u5f88\u7c7b\u4f3cJava\u8fd9\u7c7b\u5f3a\u7c7b\u578b\u8bed\u8a00\u7684class\u3002\u4e00\u5f00\u59cb\u56e0\u4e3a\u8be5C0\u5185\u4ec0\u4e48\u90fd\u6ca1\u6709\uff0c\u5c31\u662f\u7a7a\u7684\u3002<br \/>\n<img loading=\"lazy\" src=\"http:\/\/47.108.172.62\/blog\/wp-content\/uploads\/2018\/02\/1-pVnIrMZiB9iAz5sW28AixA-300x225.png\" alt=\"\" width=\"300\" height=\"225\" class=\"aligncenter size-medium wp-image-618\" srcset=\"http:\/\/www.imzouyang.com\/blog\/wp-content\/uploads\/2018\/02\/1-pVnIrMZiB9iAz5sW28AixA-300x225.png 300w, http:\/\/www.imzouyang.com\/blog\/wp-content\/uploads\/2018\/02\/1-pVnIrMZiB9iAz5sW28AixA-768x576.png 768w, http:\/\/www.imzouyang.com\/blog\/wp-content\/uploads\/2018\/02\/1-pVnIrMZiB9iAz5sW28AixA.png 1024w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><br \/>\n\u5f53\u6267\u884cPoint\u51fd\u6570\u5185\u90e8\u7b2c\u4e00\u884c\u4ee3\u7801this.x\u65f6\uff0cV8\u5c06\u4f1a\u521b\u5efa\u7b2c\u4e8c\u4e2a\u9690\u85cf\u7c7b\uff08hidden class\uff09\uff0c\u88ab\u79f0\u4f5c\u201cC1\u201d\u3002(C1\u7528\u6765\u63cf\u8ff0\u5c5e\u6027x\u5728\u5185\u5b58\u4e2d\u7684\u4f4d\u7f6e\u4fe1\u606f)\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u201cx\u201d\u5b58\u50a8\u5728\u504f\u79fb\u91cf0\u4e2d\uff08offset 0\uff09\uff0c\u8fd9\u610f\u5473\u7740\u5f53\u5c06\u5185\u5b58\u4e2d\u7684\u4e00\u4e2a\u70b9\u5bf9\u8c61\u89c6\u4e3a\u8fde\u7eed\u7684\u7f13\u51b2\u533a\u65f6\uff0c\u7b2c\u4e00\u4e2a\u504f\u79fb\u91cf\u5c06\u5bf9\u5e94\u4e8e\u5c5e\u6027\u201cx\u201d\u3002V8\u8fd8\u5c06\u4f7f\u7528\u4e00\u4e2a\u201c\u7c7b\u8f6c\u6362\u201d\u66f4\u65b0\u201cC0\u201d\uff0c\u5b83\u58f0\u660e\u5982\u679c\u5c06\u4e00\u4e2a\u5c5e\u6027\u201cx\u201d\u6dfb\u52a0\u5230\u4e00\u4e2apoint\u5bf9\u8c61\u4e2d\uff0c\u9690\u85cf\u7c7b\u5e94\u8be5\u4ece\u201cC0\u201d\u5207\u6362\u5230\u201cC1\u201d\u3002\u4e0b\u9762\u7684point\u5bf9\u8c61\u7684\u9690\u85cf\u7c7b\u73b0\u5728\u662f\u201cC1\u201d\u3002<br \/>\n<img loading=\"lazy\" src=\"http:\/\/47.108.172.62\/blog\/wp-content\/uploads\/2018\/02\/1-QsVUE3snZD9abYXccg6Sgw-300x225.png\" alt=\"\" width=\"300\" height=\"225\" class=\"aligncenter size-medium wp-image-619\" srcset=\"http:\/\/www.imzouyang.com\/blog\/wp-content\/uploads\/2018\/02\/1-QsVUE3snZD9abYXccg6Sgw-300x225.png 300w, http:\/\/www.imzouyang.com\/blog\/wp-content\/uploads\/2018\/02\/1-QsVUE3snZD9abYXccg6Sgw-768x576.png 768w, http:\/\/www.imzouyang.com\/blog\/wp-content\/uploads\/2018\/02\/1-QsVUE3snZD9abYXccg6Sgw.png 1024w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><br \/>\n\u7136\u540e\u6bcf\u5f53\u6709\u65b0\u5c5e\u6027\u88ab\u6dfb\u52a0\u8fdb\u6765\u65f6\uff0c\u5c31\u4f1a\u4ece\u4e0a\u4e00\u4e2a\u9690\u85cf\u7c7b\u5207\u6362\u5230\u5f53\u524d\u5c5e\u6027\u5bf9\u5e94\u521b\u5efa\u7684\u9690\u85cf\u7c7b\u3002\u6240\u4ee5\uff0c\u5f53\u6267\u884c\u5230this.y\u8fd9\u7b2c\u4e8c\u884c\u4ee3\u7801\u65f6\uff0c\u53c8\u4e3a\u8be5\u5bf9\u8c61\u521b\u5efa\u4e86\u4e00\u4e2a\u65b0\u5c5e\u6027y\uff0c\u6240\u4ee5V8\u5c31\u4f1a\u521b\u5efa\u51faC2\u9690\u85cf\u7c7b\uff0c\u5e76\u5c06\u9690\u85cf\u7c7b\u5207\u6362\u5230C2\uff1a<br \/>\n<img loading=\"lazy\" src=\"http:\/\/47.108.172.62\/blog\/wp-content\/uploads\/2018\/02\/1-spJ8v7GWivxZZzTAzqVPtA-300x225.png\" alt=\"\" width=\"300\" height=\"225\" class=\"aligncenter size-medium wp-image-620\" srcset=\"http:\/\/www.imzouyang.com\/blog\/wp-content\/uploads\/2018\/02\/1-spJ8v7GWivxZZzTAzqVPtA-300x225.png 300w, http:\/\/www.imzouyang.com\/blog\/wp-content\/uploads\/2018\/02\/1-spJ8v7GWivxZZzTAzqVPtA-768x576.png 768w, http:\/\/www.imzouyang.com\/blog\/wp-content\/uploads\/2018\/02\/1-spJ8v7GWivxZZzTAzqVPtA.png 1024w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><br \/>\n\u9690\u85cf\u7c7b\u4f20\u9012\u5207\u6362\u7684\u987a\u5e8f\u4f9d\u8d56\u4e8e\u5bf9\u8c61\u5185\u5c5e\u6027\u7684\u6dfb\u52a0\u987a\u5e8f\u3002<\/p>\n<p>\u63a5\u4e0b\u6765\u8bf4\u4e00\u4e0b\u8ddf\u9690\u85cf\u7c7b\u76f8\u5173\u7684\u53e6\u4e00\u6280\u672f\u3002V8\u5229\u7528\u4e86\u53e6\u4e00\u79cd\u4f18\u5316\u52a8\u6001\u7c7b\u578b\u8bed\u8a00\u7684\u6280\u672f\uff0c\u79f0\u4e3a\u5185\u8054\u7f13\u5b58\u3002\u5185\u8054\u9ad8\u901f\u7f13\u5b58\u4f9d\u8d56\u4e8e\u8fd9\u6837\u7684\u89c2\u5bdf\uff0c\u5373\u5bf9\u76f8\u540c\u65b9\u6cd5\u7684\u91cd\u590d\u8c03\u7528\u5f80\u5f80\u53d1\u751f\u5728\u540c\u4e00\u7c7b\u578b\u7684\u5bf9\u8c61\u4e0a\u3002<a href=\"https:\/\/github.com\/sq\/JSIL\/wiki\/Optimizing-dynamic-JavaScript-with-inline-caches\" rel=\"noopener noreferrer\" target=\"_blank\">\u8fd9\u91cc<\/a>\u53ef\u4ee5\u627e\u5230\u5bf9\u5185\u8054\u7f13\u5b58\u7684\u6df1\u5165\u89e3\u91ca\u3002<\/p>\n<p>\u6211\u4eec\u5c06\u8ba8\u8bba\u5185\u8054\u7f13\u5b58\u7684\u4e00\u822c\u6982\u5ff5\u3002<\/p>\n<p>\u90a3\u4e48\u5b83\u662f\u5982\u4f55\u5de5\u4f5c\u7684\u5462?V8\u5728\u6700\u8fd1\u7684\u65b9\u6cd5\u8c03\u7528\u4e2d\u5c06\u5bf9\u8c61\u7684\u7c7b\u578b\u7f13\u5b58\u4e0b\u6765\uff0c\u5e76\u5c06\u8be5\u7f13\u5b58\u4e0b\u6765\u7684\u7c7b\u578b\u4f5c\u4e3a\u53c2\u6570\u4f20\u9012\uff0c\u5e76\u4f7f\u7528\u8fd9\u4e9b\u7c7b\u578b\u7f13\u5b58\u4fe1\u606f\u5bf9\u5c06\u6765\u4f5c\u4e3a\u53c2\u6570\u4f20\u9012\u7684\u8fd9\u4e9b\u5bf9\u8c61\u7684\u7c7b\u578b\u8fdb\u884c\u4e86\u63d0\u524d\u5047\u8bbe\u3002\u5982\u679cV8\u80fd\u591f\u5bf9\u5c06\u8981\u4f20\u9012\u7ed9\u67d0\u4e2a\u65b9\u6cd5\u7684\u5bf9\u8c61\u7c7b\u578b\u505a\u51fa\u4e00\u4e2a\u826f\u597d\u7684\u5047\u8bbe\uff0c\u90a3\u4e48\u5b83\u5c31\u53ef\u4ee5\u7ed5\u8fc7\u67e5\u627e\u5982\u4f55\u8bbf\u95ee\u5bf9\u8c61\u5c5e\u6027\u7684\u8fc7\u7a0b\uff0c\u76f8\u53cd\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u524d\u67e5\u627e\u7684\u5b58\u50a8\u4fe1\u606f\u5230\u5bf9\u8c61\u7684\u9690\u85cf\u7c7b\uff0c\u4ece\u800c\u63d0\u9ad8\u8fd0\u884c\u6548\u7387\u3002<\/p>\n<p>\u90a3\u4e48\u9690\u85cf\u7c7b\u548c\u5185\u8054\u7f13\u5b58\u7684\u6709\u4ec0\u4e48\u8054\u7cfb\u5462?<\/p>\n<p>\u6bcf\u5f53\u8c03\u7528\u67d0\u4e2a\u7279\u5b9a\u5bf9\u8c61\u7684\u65b9\u6cd5\u65f6\uff0cV8\u5f15\u64ce\u5c31\u5fc5\u987b\u5bf9\u8be5\u5bf9\u8c61\u7684\u9690\u85cf\u7c7b\u6267\u884c\u67e5\u627e\uff0c\u4ee5\u786e\u5b9a\u8bbf\u95ee\u7279\u5b9a\u5c5e\u6027\u7684\u504f\u79fb\u91cf\u3002\u5728\u4e24\u6b21\u6210\u529f\u8c03\u7528\u540c\u4e00\u4e2a\u9690\u85cf\u7c7b\u7684\u65b9\u6cd5\u4e4b\u540e\uff0cV8\u7701\u7565\u4e86\u9690\u85cf\u7c7b\u67e5\u627e\uff0c\u5e76\u7b80\u5355\u5730\u5c06\u5c5e\u6027\u7684\u504f\u79fb\u91cf\u6dfb\u52a0\u5230\u5bf9\u8c61\u6307\u9488\u672c\u8eab\u3002\u5bf9\u4e8e\u8be5\u65b9\u6cd5\u7684\u6240\u6709\u672a\u6765\u8c03\u7528\uff0cV8\u5f15\u64ce\u5047\u8bbe\u9690\u85cf\u7684\u7c7b\u6ca1\u6709\u6539\u53d8\uff0c\u5e76\u76f4\u63a5\u8df3\u8f6c\u5230\u5185\u5b58\u5730\u5740\uff0c\u4ece\u800c\u63d0\u9ad8\u4e86\u8fd0\u884c\u901f\u5ea6\u3002<br \/>\n\u5f53\u6267\u884c\u65f6\u68c0\u67e5\u5230\u5185\u8054\u7f13\u5b58\u4e3a\u4e4b\u524d\u76f8\u540c\u7684\u4e00\u4e2a\uff0c\u5c31\u4f1a\u91c7\u7528\u4e4b\u524d\u7684\u9690\u85cf\u7c7b\u6765\u76f4\u63a5\u8df3\u8f6c\u5185\u5b58\u5730\u5740\u3002<\/p>\n<p>\u5f53Crankshaft\uff08\u6587\u7ae0\u5f00\u5934\u63d0\u5230\u8fc7\uff0c\u4e00\u4e2a\u8fd0\u884c\u65f6\u4f18\u5316\u8fc7\u7684\u7f16\u8bd1\u5668\uff09\u5b8c\u6210\u4e86\u4f18\u5316\uff0cCrankshaft\u628a\u5b83\u964d\u4f4e\u5230\u4e00\u4e2a\u53eb\u505aLithium\u7684\u4f4e\u7ea7\u8868\u793a\u5f62\u3002\u5927\u591a\u6570\u7684Lithium\u5b9e\u73b0\u90fd\u57fa\u4e8e\u7279\u5b9a\u4f53\u7cfb\u7ed3\u6784\u7684\u3002\u5bc4\u5b58\u5668\u5206\u914d\u53d1\u751f\u5728\u8fd9\u4e2a\u7ea7\u522b\u3002\u6700\u540e\uff0cLithium \u88ab\u7f16\u8bd1\u6210\u673a\u5668\u7801\u3002<\/p>\n<p>&emsp;<\/p>\n<h4>\u4e94\u3001<\/h4>\n<p>\u6700\u540e\uff0c\u8fd9\u91cc\u6709\u4e00\u4e9b\u5173\u4e8e\u5982\u4f55\u7f16\u5199\u4f18\u5316\u7684\u3001\u66f4\u597d\u7684JavaScript\u7684\u6280\u5de7\u3002\u4f60\u53ef\u4ee5\u5f88\u5bb9\u6613\u5730\u4ece\u4e0a\u9762\u7684\u5185\u5bb9\u4e2d\u63a8\u5bfc\u51fa\u8fd9\u4e9b\u5185\u5bb9\uff0c\u4f46\u662f\uff0c\u8fd9\u91cc\u6709\u4e00\u4e2a\u7b80\u5355\u7684\u603b\u7ed3:<br \/>\n1\u3001\u5bf9\u8c61\u5c5e\u6027\u7684\u987a\u5e8f:\u603b\u662f\u4ee5\u76f8\u540c\u7684\u987a\u5e8f\u5b9e\u4f8b\u5316\u60a8\u7684\u5bf9\u8c61\u5c5e\u6027\uff0c\u8fd9\u6837\u9690\u85cf\u7684\u7c7b\uff0c\u4ee5\u53ca\u968f\u540e\u4f18\u5316\u7684\u4ee3\u7801\uff0c\u90fd\u53ef\u4ee5\u88ab\u5171\u4eab\u3002<br \/>\n2\u3001\u52a8\u6001\u5c5e\u6027:\u5728\u5b9e\u4f8b\u5316\u4e4b\u540e\u5c06\u5c5e\u6027\u6dfb\u52a0\u5230\u5bf9\u8c61\u4e2d\uff0c\u5c06\u5f3a\u5236\u9690\u85cf\u7c7b\u66f4\u6539\uff0c\u5e76\u51cf\u6162\u5bf9\u524d\u4e00\u4e2a\u9690\u85cf\u7c7b\u8fdb\u884c\u4f18\u5316\u7684\u4efb\u4f55\u65b9\u6cd5\u3002\u76f8\u53cd\uff0c\u5728\u6784\u9020\u51fd\u6570\u4e2d\u5206\u914d\u6240\u6709\u5bf9\u8c61\u7684\u5c5e\u6027\u3002<br \/>\n3\u3001\u65b9\u6cd5:\u91cd\u590d\u6267\u884c\u76f8\u540c\u65b9\u6cd5\u7684\u4ee3\u7801\u5c06\u6bd4\u6267\u884c\u8bb8\u591a\u4e0d\u540c\u65b9\u6cd5\u7684\u4ee3\u7801\u8fd0\u884c\u5f97\u66f4\u5feb(\u7531\u4e8e\u5185\u8054\u7f13\u5b58)\u3002<br \/>\n4\u3001\u6570\u7ec4:\u907f\u514d\u7a00\u758f\u6570\u7ec4\uff0c\u5176\u4e2d\u952e\u4e0d\u662f\u9012\u589e\u7684\u6570\u5b57\u3002\u6570\u7ec4\u4e2d\u6ca1\u6709\u4efb\u4f55\u5143\u7d20\u7684\u7a00\u758f\u6570\u7ec4\u662f\u4e00\u4e2a\u54c8\u5e0c\u8868\u3002\u6b64\u7c7b\u6570\u7ec4\u4e2d\u7684\u5143\u7d20\u8bbf\u95ee\u6210\u672c\u66f4\u9ad8\u3002\u53e6\u5916\uff0c\u5c3d\u91cf\u907f\u514d\u9884\u5148\u5206\u914d\u5927\u578b\u6570\u7ec4\u3002<br \/>\n5\u3001\u6807\u8bb0\u503c:V8 \u5728\u8868\u793a\u5bf9\u8c61\u548c\u6570\u5b57\u65f6\u4f7f\u7528\u768432\u4f4d\u3002\u5b83\u4f1a\u7528\u4e00\u4f4d\u6765\u8868\u793a\u662fObject (flag = 1) \u8fd8\u662fintegar (flag = 0) \u3002\u4f59\u4e0b\u8fd8\u670931\u4f4d\uff0c\u5982\u679c\u4e00\u4e2a\u6570\u503c\u5927\u4e8e31\u4f4d\uff0cV8\u5c06\u521b\u5efa\u4e00\u4e2a\u65b0\u7684\u5bf9\u8c61\u6765\u5c06\u8fd9\u4e2a\u6570\u5b57\u653e\u5165\u91cc\u9762\uff0c\u5e76\u628a\u8be5\u6570\u5b57\u53d8\u6210\u4e00\u4e2adouble\u3002\u6240\u4ee5\u5c3d\u53ef\u80fd\u4f7f\u752831\u4f4d\u4ee5\u5185\u6570\u5b57\uff0c\u4ee5\u907f\u514d\u6602\u8d35\u5f00\u9500\u4ea7\u751f\u3002<\/p>\n<p>&emsp;<\/p>\n<p>PS\uff1a<br \/>\n<a href=\"https:\/\/docs.google.com\/document\/u\/1\/d\/1hOaE7vbwdLLXWj3C8hTnnkpE0qSa2P--dtDvwXXEeD0\/pub\" rel=\"noopener noreferrer\" target=\"_blank\">https:\/\/docs.google.com\/document\/u\/1\/d\/1hOaE7vbwdLLXWj3C8hTnnkpE0qSa2P&#8211;dtDvwXXEeD0\/pub<\/a><br \/>\n<a href=\"https:\/\/github.com\/thlorenz\/v8-perf\" rel=\"noopener noreferrer\" target=\"_blank\">https:\/\/github.com\/thlorenz\/v8-perf<\/a><br \/>\n<a href=\"http:\/\/code.google.com\/p\/v8\/wiki\/UsingGit\" rel=\"noopener noreferrer\" target=\"_blank\">http:\/\/code.google.com\/p\/v8\/wiki\/UsingGit<\/a><br \/>\n<a href=\"http:\/\/mrale.ph\/v8\/resources.html\" rel=\"noopener noreferrer\" target=\"_blank\">http:\/\/mrale.ph\/v8\/resources.html<\/a><br \/>\n<a href=\"https:\/\/www.youtube.com\/watch?v=UJPdhx5zTaw\" rel=\"noopener noreferrer\" target=\"_blank\">https:\/\/www.youtube.com\/watch?v=UJPdhx5zTaw<\/a><br \/>\n<a href=\"https:\/\/www.youtube.com\/watch?v=hWhMKalEicY\" rel=\"noopener noreferrer\" target=\"_blank\">https:\/\/www.youtube.com\/watch?v=hWhMKalEicY<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u524d\u4e00\u7bc7\u6587\u7ae0JavaScript\u6df1\u5c42\u5de5\u4f5c\u539f\u7406\u89e3\u6790(\u4e00)\u4e2d\uff0c\u6211\u4eec\u6982\u89c8\u4e86js\u8fd0\u884c\u7684\u5f15\u64ce\u3001\u8fd0\u884c\u73af\u5883\u3001\u8c03\u7528\u6808\u3002 \u672c\u7bc7\u5c06\u6df1 &hellip; <a href=\"http:\/\/www.imzouyang.com\/blog\/archives\/593.html\" class=\"read-more\">\u7ee7\u7eed\u9605\u8bfb <span class=\"screen-reader-text sr-only\">\u5f15\u64ce\u4e0e\u73af\u5883(\u4e8c):\u6df1\u5165V8\u5f15\u64ce+\u5982\u4f55\u4e66\u5199\u6027\u80fd\u5f3a\u52b2\u7684\u4ee3\u7801<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"aside","meta":[],"categories":[30],"tags":[],"_links":{"self":[{"href":"http:\/\/www.imzouyang.com\/blog\/wp-json\/wp\/v2\/posts\/593"}],"collection":[{"href":"http:\/\/www.imzouyang.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.imzouyang.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.imzouyang.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.imzouyang.com\/blog\/wp-json\/wp\/v2\/comments?post=593"}],"version-history":[{"count":2,"href":"http:\/\/www.imzouyang.com\/blog\/wp-json\/wp\/v2\/posts\/593\/revisions"}],"predecessor-version":[{"id":2058,"href":"http:\/\/www.imzouyang.com\/blog\/wp-json\/wp\/v2\/posts\/593\/revisions\/2058"}],"wp:attachment":[{"href":"http:\/\/www.imzouyang.com\/blog\/wp-json\/wp\/v2\/media?parent=593"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.imzouyang.com\/blog\/wp-json\/wp\/v2\/categories?post=593"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.imzouyang.com\/blog\/wp-json\/wp\/v2\/tags?post=593"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}