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Investigate the relationship between the storage and function of JavaScript tags.

Source: Internet
Author: User
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Investigate the relationship between the storage and function of JavaScript tags.

On a webpage, we can place JavaScript code anywhere in an html file, but generally in a head or body tag.

In general, where <script> elements are placed is closely related to their functions. Here we will discuss two situations:

1. Put it in

The <script> element is placed in the head to allow the browser to read from the beginning. The <script> element is loaded and executed at the beginning of the parsing of the entire webpage, its priority is second only to <title> elements.

Then parse the rendering in sequence.

Application: for example, JavaScript code for page display initialization must be placed in the head.

2. In the <body> section

The browser parses the Code in order of page tags. When the JavaScript code is read, the statement is executed.

However, some JS functions are called through events, so the specific location on the page does not affect the time when the function is applied. Therefore, considering the front-end performance problems, you can put the JS Code that is not the first execution and event call at the bottom of the body.

Write and read:

<! Doctype html> 

As you can see above, the storage and function of javascript labels are closely related. I hope this article will help you.

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