What are the things JavaScript can do on a website when added?

Answer 1

I would say: Primarily the use is to access the DOM and to provide dynamic contents.

Answer 2

JavaScript is a client scripting language which is used for creating web pages. It is a standalone language developed in Netscape. It is used when a webpage is to be made dynamic and add special effects on pages like rollover, roll out and many types of graphics.

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