Why we should avoid use of Java scripts?

[259]

I always here we should avoid use of java scripts from the seo prospective, What is the exact reason, what effect it will give to website ranking if it is used in numbers?

[Chris]

It depends on what JavaScript does on the page. If it is basically building the site, that's bad.
The reason is that SEO depends on a page being more or less in its final form even if JavaScript were not activated in the browser, because the robots that crawl pages don't run JavaScript functions, they just look at the raw HTML code they get from the server.

Imagine a page where at first, it displays only a loading screen, and using JavaScript, proceeds to load the page in the background, then removes the loading screen. All a robot would see is the loading screen, no other data, no content, nothing.

But a generic statement like "for SEO, you should avoid JavaScript" is much too broad (as long as, like I said, JavaScript is mostly used for visual effects and the like).

[Linda]

CSS replaced to Javascript. Search engine bots unable to read javascript. It will increase your website load time and size of web pages. If you require java script, try to call externally.

[J]

It increases page load speed that effect your google ranking!