Home > Article > Web Front-end > Summary of for loop performance optimization in JS
This article introduces to you a summary of for loop performance optimization in JS. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.
We really use too many FOR loops, but have you paid attention to its optimized writing? Record:
1. The most common way of writing, there is nothing wrong with it
for (var i = 0; i < 10; i++) { // do something...}
2. The number of loops is variable Situation
for (var i = 0; i < arr.length; i++) { // do something...}
In fact, most people write this way. The disadvantage of this way of writing is that the array must be read every time it loops The length is not cost-effective
3. Optimized writing of variables
for (var i = 0, l = arr.length; i < l; i++) { // do something...}
Store the length and then loop No need to read the length
4. The above 3 can also be written like this
var i = 0, l = arr.length; for (; i < l; i++) { // do something...}
This is just 3 It's just a variation of, another way of writing, not optimization at all. Because there is no block-level scope, the effect is the same as 3
5. Optimized writing and upgraded version
for (var i = arr.length - 1; i >= 0; i--) { // do something...}
Recommended writing method, which saves a variable based on the third method.
Recommended related articles:
How to convert vue.js images to Base64, upload images and preview
js thread case - to achieve randomness Speed typewriter effect
The above is the detailed content of Summary of for loop performance optimization in JS. For more information, please follow other related articles on the PHP Chinese website!