How to optimize the javascript in the page

Today Xiaobian to share with you how to optimize the page javascript related knowledge points, detailed content, clear logic, I believe most people are still too familiar with this knowledge, so share this article for your reference, I hope you have read this article after harvest, let's learn about it together.

1. Introduction to JavaScript

JavaScript is extremely unfriendly to both ordinary users and search engines. Most search engines currently do not parse JavaScript generated content (i.e. JavaScript generated content is invisible to search engines). Try to avoid JavaScript when planning pages.

Until now, search engines did not parse JavaScript generated pages or content.

JavaScript code is lengthy and executes much less efficiently than HTML, resulting in pages that take too long to open.

2. JavaScript optimization

In SEO, JavaScript optimization is not about improving the efficiency of JavaScript code execution, but about avoiding JavaScript code taking up space and important places on the page. To do this, simply change where JavaScript code appears and how it is invoked. In addition, another purpose of JavaScript optimization is to take advantage of JavaScript's invisible nature to search engines to invoke content that you don't want search engines to crawl, such as Flash.

Taking advantage of the invisibility of JavaScript content to search engines, we can use JavaScript to generate content that is visible only to users.

3. JavaScript call mode

JavaScript calls are divided into internal calls and external calls, and internal calls are divided into head calls and bottom calls.

head call

A header call is to place JavaScript code at the head of the page. However, a large amount of JavaScript code placed at the head of the page will not only increase the size of the page, but also occupy an important position at the top of the page, so that the relatively important content in the page cannot be displayed to the search engine first, as shown in the following code:

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