Phantom JS-如何获得性能计时？

Question

With PhantomJS, I want to gather perfomance timing on page load time.

I test this 2 methods for gathering metrics

Setting own timing

var page = require('webpage').create();   
var system = require('system');
var loadingTime;

loadingTime = Date.now();
page.open('http://crawlbin.com', function (status) {
     loadingTime = Date.now() - loadingTime;
     console.log('Loading time ' + loadingTime + ' msec');
     phantom.exit();
});

Result : Loading time 499 msec

Using W3C Navigation Timing

var page = require('webpage').create();   
var system = require('system');

page.open('http://crawlbin.com', function (status) {
     console.log(window.performance.timing.loadEventEnd - window.performance.timing.navigationStart); 
     phantom.exit();
});

Result : 256

But I don't get the same result. Navigation Timing is always less than own timing and Navigation Timing has a much lower value.

What is the most accurate measurement?

Answer 1

Regrettably, there is something wrong with the way window.performance.navigationStart is set in the performance timeline. I don't know enough C++ to have pinpointed the issue, but I have opened a defect.

I know this isn't an answer, but if all you're looking for is the loadEventEnd timing, what you're capturing in your first instance is as close a representation of the client timing you're trying to measure.

For reference, the defect is here - https://github.com/ariya/phantomjs/issues/13093