{"id":769,"date":"2018-12-08T23:58:55","date_gmt":"2018-12-08T15:58:55","guid":{"rendered":"https:\/\/sora.sound.moe\/?p=769"},"modified":"2018-12-08T23:58:55","modified_gmt":"2018-12-08T15:58:55","slug":"javascript-%e4%bd%bf%e7%94%a8-proxy-%e5%8a%ab%e6%8c%81%e4%bb%bb%e6%84%8f%e5%87%bd%e6%95%b0%e6%89%a7%e8%a1%8c","status":"publish","type":"post","link":"https:\/\/sora.sound.moe\/?p=769","title":{"rendered":"JavaScript \u4f7f\u7528 Proxy \u52ab\u6301\u4efb\u610f\u51fd\u6570\u6267\u884c"},"content":{"rendered":"\n\n\n\n\n

\u5728\u5b9e\u9645\u4f7f\u7528\u4e2d\u6709\u4e00\u4e2a\u5947\u602a\u7684\u9700\u6c42\u3002\u6211\u9700\u8981\u52ab\u6301XMLHttpRequest.prototype.open<\/code>\u6765\u76d1\u63a7\u5168\u90e8\u7684\u8bf7\u6c42\u5185\u5bb9\u3002<\/p>\n\n\n\n

\u4ee5\u5f80\u5e38\u7528\u7684\u52ab\u6301\u65b9\u6cd5\u662f\u8fd9\u6837\u7684<\/p>\n\n\n\n

const originalOpen = XMLHttpRequest.prototype.open;

XMLHttpRequest.prototype.open = function() {
    \/\/ do something;
    originalOpen.apply(this, arguments);
}

<\/pre>\n\n\n\n
\u8fd9\u6837\u505a\u786e\u5b9e\u662f\u53ef\u4ee5\u505a\u5230\uff0c\u4f46\u662f\u5b58\u5728\u4e00\u4e2a\u95ee\u9898\uff1a\u5982\u679c XMLHttpRequest.prototype.open<\/code>\u88ab\u7b2c\u4e09\u8005\u91cd\u65b0\u8986\u76d6\u6389\u4e86\uff0c\u6211\u4eec\u5c31\u6ca1\u6cd5\u76d1\u89c6\u65b9\u6cd5\u7684\u6267\u884c\u4e86\u3002<\/p>\n\n\n\n
\u5f88\u81ea\u7136\u60f3\u5230\u53bb\u76d1\u89c6\u8fd9\u4e2a\u201c\u8986\u76d6\u201d\u64cd\u4f5c\uff0c\u5728\u88ab\u8986\u76d6\u7684\u65f6\u5019\u5f80\u522b\u4eba\u8eab\u4e0a\u63d2\u70b9\u4ee3\u7801\uff0c\u4f46\u662f\u7814\u7a76\u4e86\u534a\u5929\uff0c\u60f3\u8981\u5b9e\u73b0\u8fd9\u4e2a\u6709\u4e00\u70b9\u95ee\u9898\u3002<\/p>\n\n\n\n
\u76d1\u63a7\u5bf9\u8c61\u7684\u5c5e\u6027\u88ab\u8d4b\u503c\uff0c\u53ef\u4ee5\u4f7f\u7528Proxy<\/code>\u3002\u4f46\u662fXMLHttpRequest.prototype<\/code>\u662fwritable: false, configurable: false<\/code>\u7684\uff0c\u8986\u76d6\u5b83\u5e76\u65e0\u6548\u679c\u3002<\/p>\n\n\n\n
\"\"<\/figure>\n\n\n\n
\u90a3\u4e48\u6211\u4eec\u8fd8\u6709\u53e6\u4e00\u79cd\u65b9\u6cd5\u5c31\u662f\u4f7f\u7528 setter \u6765\u76d1\u89c6\u8d4b\u503c\u64cd\u4f5c\u3002<\/p>\n\n\n\n
\u6211\u4eec\u80fd\u4e0d\u80fd\u7ed9XMLHttpRequest.prototype.open<\/code>\u65b0\u5efa\u4e00\u4e2asetter\u5728\u4e0d\u5f71\u54cd\u5b83\u539f\u6765\u503c\u7684\u60c5\u51b5\u4e0b\u76d1\u89c6\u5b83\u88ab\u8d4b\u503c\u5462\uff0c\u7b54\u6848\u662f\u4e0d\u53ef\u4ee5\u3002\u6211\u4eec\u9700\u8981\u5148\u5907\u4efd\u539f\u503c\u3002<\/p>\n\n\n\n
\n\nXMLHttpRequest.prototype._open = XMLHttpRequest.prototype.open;\n\n<\/pre>\n\n\n\n
\u4e3a\u4e86\u9632\u6b62\u81ea\u6211\u8c03\u7528\u65e0\u9650\u5faa\u73af\uff0c\u4f7f\u7528 _open \u6765\u5b58\u50a8\u539f\u6765\u7684\u503c\u3002\u540c\u65f6\u5b9a\u4e49\u4e00\u4e2a\u65b0\u7684 getter \u91cd\u5b9a\u5411\u5bf9\u539f open \u7684\u8c03\u7528\u3002<\/p>\n\n\n\n
\u76d1\u89c6\u5230\u8d4b\u503c\u64cd\u4f5c\u4e4b\u540e\u5c31\u9700\u8981\u5728\u76d6\u4e0a\u6765\u7684\u4e1c\u897f\u4e0a\u6302\u70b9\u81ea\u5df1\u7684\u4e1c\u897f\uff0c\u6700\u7ec8\u6211\u4eec\u8fd8\u662f\u4f7f\u7528 Proxy<\/code>\u7684handler.apply<\/code>\u6765\u52ab\u6301\u51fd\u6570\u7684\u201c\u6267\u884c\u201d\u8fd9\u4e00\u52a8\u4f5c\u3002handler.apply<\/code>\u7b2c\u4e00\u4e2a\u53c2\u6570\u662f\u88ab\u6267\u884c\u7684\u51fd\u6570\uff0c\u7b2c\u4e8c\u4e2a\u53c2\u6570\u662fcallee<\/code>\uff0c\u4e3a\u4e0d\u5f71\u54cd\u5176\u539f\u6709\u529f\u80fd\uff0c\u7528Function.prototype.call<\/code>\u6765\u624b\u52a8\u6307\u5b9a\u5b83\u7684this<\/code>\uff0c\u7b2c\u4e09\u53c2\u6570\u4e3a\u8c03\u7528 f \u65f6\u4f20\u5165\u7684\u53c2\u6570\u7684\u6570\u7ec4<\/strong>\u3002\u6ce8\u610f\u662f\u6570\u7ec4\u2026\u2026\u4f20\u8fdb\u51fd\u6570\u7684\u65f6\u5019\u6ce8\u610f\u8981\u5c55\u5f00\uff0c\u5751\u4e86\u6211\u597d\u4e00\u4f1a\u513f\uff08\u56e0\u4e3a\u662f\u5728\u5b9e\u9645\u5e94\u7528\u73af\u5883\u4e0b\u64cd\u4f5c\u7684\uff0c\u6709\u70b9\u590d\u6742\u4e0d\u597d\u8c03\u8bd5\uff09\u3002<\/p>\n\n\n\n

Object.defineProperty(XMLHttpRequest.prototype, 'open', {
        get: function () {
            return this._open;
        },
        set: function (f) {
            this._open = new Proxy(f, {
                apply: function(f, instance, fargs) {
                    listen.call(instance, ...fargs);
                    return f.call(instance, ...fargs)
                }
            });
        }
    });<\/pre>\n\n\n\n
\u6700\u7ec8\u6211\u4eec\u5f97\u5230\u7c7b\u4f3c\u4e8e\u4e0a\u9762\u7684\u4ee3\u7801\u3002\u5728\u4e0d\u5f71\u54cd\u539f\u6765\u51fd\u6570\u529f\u80fd\u7684\u60c5\u51b5\u4e0b\u63d2\u5165\u4e86\u4e00\u6bb5\u81ea\u5df1\u7684listen<\/code>\u4ee3\u7801\uff0c\u6211\u597d\u4e86\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[2],"tags":[],"uagb_featured_image_src":{"full":false,"thumbnail":false,"medium":false,"medium_large":false,"large":false,"1536x1536":false,"2048x2048":false,"twentyseventeen-featured-image":false,"twentyseventeen-thumbnail-avatar":false},"uagb_author_info":{"display_name":"Sora","author_link":"https:\/\/sora.sound.moe\/?author=1"},"uagb_comment_info":1,"uagb_excerpt":null,"_links":{"self":[{"href":"https:\/\/sora.sound.moe\/index.php?rest_route=\/wp\/v2\/posts\/769"}],"collection":[{"href":"https:\/\/sora.sound.moe\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sora.sound.moe\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sora.sound.moe\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/sora.sound.moe\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=769"}],"version-history":[{"count":0,"href":"https:\/\/sora.sound.moe\/index.php?rest_route=\/wp\/v2\/posts\/769\/revisions"}],"wp:attachment":[{"href":"https:\/\/sora.sound.moe\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=769"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sora.sound.moe\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=769"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sora.sound.moe\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=769"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}