Example of how JS uses console to calculate code running time

I recently read a book and found a method for calculating code execution time. I think it is quite useful, so this article mainly introduces you to how Javascript uses console to calculate code execution time. The relevant information is introduced in great detail through js sample code. Friends who are interested in JavaScript can refer to this article.

Preface

This article mainly introduces to you the relevant content about Js using console to calculate the code running time, and shares it for your reference and study. Not much to say below, let’s take a look at the detailed introduction.

Requirements

If you learn the front-end for a certain period of time, you will consider performance issues. So the question is, how do we calculate the running time of a piece of code?

Use console.log with Dateobjectcalculation

For example, we calculate## If the #sort method takes how long it takes to sort an array of 100,000 random arrays, you can write it like this:

    var arr = [];
    for(var i=0; i<100000; i++){
      arr.push(Math.random());
    }
    var beginTime = +new Date();
    arr.sort();
    var endTime = +new Date();
    console.log("排序用时共计"+(endTime-beginTime)+"ms");

Finally, it will be displayed on the console:

排序用时共计552ms

Below, we introduce a more flexible and accurate method.

Use console.time for time calculation

This method is more accurate than the previous one and is specifically generated for performance:

Test case:

    var arr = [];
    for(var i=0; i<100000; i++){
      arr.push(Math.random());
    }
    console.time("sort");
    arr.sort();
    console.timeEnd("sort");

The console will print out:

sort: 542.668701171875ms

This method writes console.time at the beginning of the test and passes a

string in brackets . Use the console.timeEnd method at the end and pass in the string again.

Personally recommend the second way.

Summary

The above is all the content of this article, I hope it can help everyone learn! !

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