Javascript 如何测量脚本的执行时间？
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How can I measure the execution time of a script?
提问by Skizit
How would I measure the time it takes for a script to run from start to finish?
我将如何衡量脚本从头到尾运行所需的时间？
start-timing
//CODE
end-timing
回答by Arnaud Le Blanc
EDIT: in January 2011, this was the best available solution. Other solutions (such as performance.now()should be preferred now.
编辑：2011 年 1 月，这是最好的可用解决方案。其他解决方案（例如performance.now()现在应该首选。
var start = new Date();
// CODE
var time = new Date() - start;
// time is the number of milliseconds it taken to execute the script
You may also want to wrap that in a function:
您可能还想将其包装在一个函数中：
function time_my_script(script) {
var start = new Date();
script();
return new Date() - start;
}
// call it like this:
time = time_my_script(function() {
// CODE
});
// or just like this:
time = time_my_script(func);
If you are trying to profile your code, you may want to try the Firebugextension, which includes a javascript profiler. It has a great user interface for profiling, but it also can be done programmatically with its console api :
如果您正在尝试分析您的代码，您可能想要尝试Firebug扩展，它包括一个 javascript 分析器。它具有用于分析的出色用户界面，但也可以使用其控制台 api以编程方式完成：
console.time('timer1');
// CODE
console.timeEnd('timer1'); // this prints times on the console
console.profile('profile1');
// CODE
console.profileEnd('profile1'); // this prints usual profiling informations, per function, etc.
回答by Morteza Ziyae
Use performance.now()instead of new Date(). This provides a more accurate and better result. See this answer https://stackoverflow.com/a/15641427/730000
使用performance.now()代替new Date()。这提供了更准确和更好的结果。请参阅此答案https://stackoverflow.com/a/15641427/730000
回答by Steven Kaspar
Here is a quick function to work like a stopwatch
这是一个像秒表一样工作的快速功能
var Timer = function(id){
var self = this;
self.id = id;
var _times = [];
self.start = function(){
var time = performance.now();
console.log('[' + id + '] Start');
_times.push(time);
}
self.lap = function(time){
time = time ? time: performance.now();
console.log('[' + id + '] Lap ' + time - _times[_times.length - 1]);
_times.push(time);
}
self.stop = function(){
var time = performance.now();
if(_times.length > 1){
self.lap(time);
}
console.log('[' + id + '] Stop ' + (time - _times[0]));
_times = [];
}
}
// called with
var timer = new Timer('process label');
timer.start(); // logs => '[process label] Start'
// ... code ...
timer.lap(); // logs => '[process label] Lap ' + lap_time
// ... code ...
timer.stop(); // logs => '[process label] Stop ' + start_stop_diff
回答by adardesign
Use the User Timing api
使用用户计时 api
For example:
in the beginningof the JS file write: performance.mark("start-script")
例如：在JS文件的开头写：performance.mark("start-script")
at the endof the JS file write: performance.mark("end-script")
在结束JS文件写的：performance.mark("end-script")
then you can measure it too:
那么你也可以测量它：
performance.measure("total-script-execution-time", "start-script", "end-script");
performance.measure("total-script-execution-time", "start-script", "end-script");
This will give you the time it takes to run the entire script execution.
这将为您提供运行整个脚本执行所需的时间。
