如何收集常见的前端性能信息

  1 <script>
  2     ;(function(window, undefined) {
  3         function addEvent(type, fn) {
  4             if (window.addEventListener) {
  5                 window.addEventListener(type, fn, false);
  6             } else {
  7                 window.attachEvent(‘on‘ + type, fn);
  8             }
  9         }
 10 
 11         // load 事件触发猴再收集相关数据
 12         addEvent(‘load‘, getTiming);
 13 
 14         // 快捷入口
 15         window.getTiming = getTiming;
 16 
 17         function getTiming() {
 18             // 浏览器支持的API
 19             var performance = window.performance;
 20 
 21             if (!performance || !performance.timing) {
 22                 console.log(‘当前浏览器不支持Performance Time API‘);
 23                 return;
 24             }
 25 
 26             var timing = performance.timing,
 27                 timings = {
 28                     page: [],
 29                     pageReport: []
 30                 };
 31 
 32             // 设置某一项耗时统计
 33             function setPageTiming(name, text, time) {
 34                 timings.page.push({
 35                     name: name,
 36                     text: text,
 37                     time: time + ‘ ms‘
 38                 });
 39 
 40                 timings.pageReport.push({
 41                     name: name,
 42                     time: time + ‘ ms‘
 43                 });
 44             }
 45 
 46             // 页面加载仍未完成，loadEventEnd值可能为0，需要延迟处理
 47             if (timing.loadEventEnd - timing.navigationStart < 0) {
 48                 console.log(‘getTiming delay‘);
 49                 setTimeout(getTiming, 1000);
 50                 return;
 51             }
 52 
 53             setPageTiming(‘redirect‘, ‘重定向‘, timing.redirectEnd - timing.redirectStart);
 54             setPageTiming(‘dns‘, ‘DNS解析‘, timing.domainLookupEnd - timing.domainLookupStart);
 55             setPageTiming(‘tcp‘, ‘TCP连接‘, timing.connectEnd - timing.connectStart);
 56             setPageTiming(‘ssl‘, ‘TCP-SSL连接‘, !timing.secureConnectionStart ? 0 : timing.connectEnd - timing.secureConnectionStart);
 57             setPageTiming(‘ttfb‘, ‘TTFB服务器返回首个字节‘, timing.responseStart - timing.requestStart);
 58             setPageTiming(‘download‘, ‘DOM资源下载‘, timing.responseEnd - timing.responseStart);
 59             setPageTiming(‘before-parse-html‘, ‘DOM解析前耗时‘, timing.responseEnd - timing.navigationStart);
 60             setPageTiming(‘html-parsed‘, ‘DOM解析完成‘, timing.domInteractive - timing.domLoading);
 61             setPageTiming(‘dom-loaded‘, ‘DOM加载完成‘, timing.domComplete - timing.domLoading);
 62             setPageTiming(‘dom-content-load‘, ‘DOMContentLoaded事件开始‘, timing.domContentLoadedEventStart - timing.navigationStart);
 63             setPageTiming(‘dom-content-loaded‘, ‘DOMContentLoaded事件结束‘, timing.domContentLoadedEventEnd - timing.navigationStart);
 64             setPageTiming(‘load‘, ‘Load事件开始‘, timing.loadEventStart - timing.navigationStart);
 65             setPageTiming(‘loaded‘, ‘Load事件结束‘, timing.loadEventEnd - timing.navigationStart);
 66 
 67             // 以下两项可以直接获取
 68             var paintTiming = {
 69                 ‘first-paint‘: ‘首屏（首次绘制）‘,
 70                 ‘first-contentful-paint‘: ‘首屏（首次内容绘制）‘
 71             };
 72 
 73             performance.getEntriesByType(‘paint‘).forEach(function(entry) {
 74                 if (paintTiming[entry.name]) {
 75                     setPageTiming(entry.name, paintTiming[entry.name], entry.startTime + entry.duration);
 76                 }
 77             });
 78 
 79             // 以下两项指标与需求有关，需要根据业务要求在代码中打点统计
 80             // setPageTiming(‘first-meaningful-paint‘, ‘首屏（首次有效绘制）‘, timing.domInteractive - timing.navigationStart);
 81             // setPageTiming(‘time-to-interactive‘, ‘可交互时间‘, timing.domInteractive - timing.navigationStart);
 82 
 83             // 简易版统计上报
 84             if (requestIdleCallback) {
 85                 requestIdleCallback(function() {
 86                     report(timings.pageReport);
 87                 });
 88             } else {
 89                 setTimeout(function() {
 90                     report(timings.pageReport);
 91                 });
 92             }
 93 
 94             function report(data) {
 95                 data = data || [];
 96 
 97                 if (!data.length) {
 98                     return;
 99                 }
100 
101                 (new Image()).src = ‘https://a.b.c/d/e?t=‘ + (new Date())
102                     + ‘&l=‘ + location.href
103                     + ‘&p=‘ + navigator.platform
104                     + ‘&net=‘ + navigator.connection.effectiveType
105                     + ‘&u=‘ + navigator.userAgent
106                     + ‘&times=‘ + JSON.stringify(data);
107             }
108 
109             console.table(timings.page);
110             console.log(performance.timing);
111         }
112     })(window);
113 </script>