Lazy loading JavaScript

How to Lazy Load JavaScript

True lazy loading of JavaScript means: loading or parsing JavaScript only after the page content has been fully loaded (this means that JavaScript cannot affect page speed or criticality) rendering path).

• Use the "onload" event to call external JavaScript resources

• External JavaScript resources cannot be loaded before the page content is loaded

• External JavaScript resources do not start running until the content is loaded and affect the page

Explanation

The focus on the Internet is often people trying to find a Crazy about various solutions, JavaScript lazy loading is one of the focuses.

Many people say "just use defer", "just use async", or "just put your JavaScript at the bottom of the page", but these are not solved Problem - Let the page fully load and then (only after fully loading) load the external JS. These methods will also not let you pass the "delayed loading JavaScript" warning obtained from the Google Page Speed ​​Tool (the translator has some doubts about this, because during testing I found that the above three methods can remove this warning).

This solution will answer.

Script that calls an external JavaScript file

This code is placed before the