Firefox engine is named SpiderMonkey,
Chrome has a V8 engine, and
IE has Chakra.
Companies like Netflix, PayPal, Walmart etc., heavily use it.
1. Validate user input
Almost all web applications accept user input such as a registration form, booking details, Captcha verification etc.
User can input any data that needs to be validated before saving it and many times it is not affordable (due to network bandwidth or security measures) to send the data to the server, validate it there and send error message if the data is invalid.
2. Making applications dynamic
Example, registration form should be displayed only when user opts to register.
3. Validate missing values
4. Dynamic server interaction
Suppose there is an application which asks you for your phone number and fetches your entire details registered with this number.
With AJAX support in javascipt, it can interact with the backend server, fetch and show the details right below without actually refreshing the page enhancing user experience.
5. Autocomplete input options
When typing a search string in Google, it displays a list of keywords related to the search string while typing. How convenient it seems!!!
6. Adding animations
Many consider it as same language, many think they are different.
But wait!!! both are not true.
ECMAScript is not a programming language, it is a specification defined by an organization named Ecma.
const for variable declarations etc.
Since it had major new inclusions, it came to be known ES6(due to 6th edition).