There are 3 standard web technologies used to make any web page. 

• HTML ( use to structure and add things to your web page )
• CSS ( use to style your web page like font-size, font-color )
• Javascript ( use to update your web page dynamically )

 

 

IMPORTANCE

• Javascript is a programming language which used to load or display the dynamic content easily to your web page. 
• This is the only language which you can use as a front-end and back-end language to create your web page, if you are using any other language for your back-end, still you have to use javascript as your front-end to make it properly.   
• You can use it with other frameworks also. Like you can use it with COCOS JS ( gaming engine ) to make web games.
• It can be used for lots of validations also.

Some famous Frameworks depends upon Javascript

• jQuery

jQuery is a JS library which is used to manipulate the structure of HTML DOM, also used for animation, event handling etc.

• Node.js

It is used as server-side scripting which uses JS to write command line tools.

• Angular.js

It is a front-end web framework mainly maintained by Google and a community of individuals to address many of the challenges encountered in developing single-page apps.

• React.js

It is a JS library which is used for building User Interface components. It is maintained by Facebook and a community of individuals. Major use of React is that it can make a single-page app just by using components.

 

 

Big companies which use Javascript

• PayPal ( shifted its entire back-end to Javascript from Java) 
• Facebook ( built its mobile app using React.js )
• Netflix
• Google
• Microsoft
• Walmart