HTML5的学习--performance获取加载时间的工具

 


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;// onload时，触发times方法