加载时常统计

var times = function() {
var timing = performance.timing;
var loadTime = timing.loadEventEnd - timing.navigationStart;//过早获取时,loadEventEnd有时会是0
if(loadTime <= 0) {
// 未加载完，延迟200ms后继续times方法，直到成功
setTimeout(function(){
times();
}, 200);
return;
}
var readyStart = timing.fetchStart - timing.navigationStart;
var redirectTime = timing.redirectEnd - timing.redirectStart;
var appcacheTime = timing.domainLookupStart - timing.fetchStart;
var unloadEventTime = timing.unloadEventEnd - timing.unloadEventStart;
var lookupDomainTime = timing.domainLookupEnd - timing.domainLookupStart;
var connectTime = timing.connectEnd - timing.connectStart;
var requestTime = timing.responseEnd - timing.requestStart;
var initDomTreeTime = timing.domInteractive - timing.responseEnd;
var domReadyTime = timing.domComplete - timing.domInteractive; //过早获取时,domComplete有时会是0
var loadEventTime = timing.loadEventEnd - timing.loadEventStart;

// 为console.table方法准备对象，包含耗时的描述和消耗的时间
var allTimes = [
    { "描述": "准备新页面时间耗时", "时间(ms)": readyStart },
    { "描述": "redirect 重定向耗时", "时间(ms)": redirectTime },
    { "描述": "Appcache 耗时", "时间(ms)": appcacheTime },
    { "描述": "unload 前文档耗时", "时间(ms)": unloadEventTime },
    { "描述": "DNS 查询耗时", "时间(ms)": lookupDomainTime },
    { "描述": "TCP连接耗时", "时间(ms)": connectTime },
    { "描述": "request请求耗时", "时间(ms)": requestTime },
    { "描述": "请求完毕至DOM加载", "时间(ms)": initDomTreeTime },
    { "描述": "解释dom树耗时", "时间(ms)": domReadyTime },
    { "描述": "load事件耗时", "时间(ms)": loadEventTime },
    { "描述": "从开始至load总耗时", "时间(ms)": loadTime }
];
console.table(allTimes);

}
window.onload = times;