What is JavaScript? - Node.js Complete Tutorial - Tamil

What is JavaScript?
JavaScript History?
ECMA is the standard for JavaScript.

JavaScript was invented by Brendan Eich in 1995.

It was developed for Netscape 2, and became the ECMA-262 standard in 1997.
What is JavaScript?
JavaScript (JS) is a lightweight, interpreted, or just-in-time compiled programming language with first-class functions.

JavaScript is a prototype-based, multi-paradigm, single-threaded, dynamic language, supporting object-oriented, imperative, and declarative (e.g. functional programming) styles.

While it is most well-known as the scripting language for Web pages, many non-browser environments also use it, such as Node.js, Apache CouchDB and Adobe Acrobat.
Lightweight
JavaScript is a lightweight programming language because it has low memory usage, simple syntax & and features, and is easy to implement.

Its popularity has exploded as developers can easily start learning and because it’s become even more powerful yet remains so lightweight.
Interpreted, or just-in-time compiled programming language
It is a way of executing computer code that involves compilation during execution of a program (at run time) rather than before execution.

i.e. You can run JavaScript directly in browser without compilation. But in other languages such .net or java – you have to compile first and then execute the code.
First-class Function
A programming language is said to have First-class functions when functions in that language are treated like any other variable.

For example, in such a language, a function can be passed as an argument to other functions, can be returned by another function and can be assigned as a value to a variable.



Prototype-based programming
Dynamic Language

The interpreter assigns variables a type at runtime based on the variable's value at the time.

We can change the existing variable, assign different datatype, create new variable during runtime.

It also means that JS does not require the explicit declaration of the variables before they’re used.
JavaScript
Python
Ruby
PHP
Lua
Perl etc.
References
https://developer.mozilla.org/en-US/docs/Web/JavaScript
https://en.wikipedia.org/wiki/Just-in-time_compilation
https://developer.mozilla.org/en-US/docs/Glossary/Prototype-based_programming
https://developer.mozilla.org/en-US/docs/Glossary/Dynamic_typing