Javascript Overview

Javascript is a high-level just-in-time compiled programming language that conforms to ECMAScript specification

Javascript alongside HTML & CSS is one of the core technologies of the web - Web browsers have a dedicated javascript engine.

JS is a dynamically typed language - you don't need to declare the types of variables. It is automatically converted as needed during execution.

There are 2 ways to run javascript

In browser - Chrome developer window
- Press F12 to activate, and enter javascript in the console tab.
- Embed it into your HTML <script> </script> tag - It will run when you open the HTML file in your browser.
- Create a file index.js, write your JS code in there and link to HTML file using the <script src='index.js'> </script>. - It will run when you open the HTML file in your browser.
Node.js runtime
- Run JS file using - $ node <filename>.js

// this is a js comment

let - a mutable variable

const - an immutable variable that always needs to be initialised

Primitive types	non-primitive types
String
`const name = ‘Jeff’`	Objects - key-value pairs
`let person = {
'name':''jeff,
'age' = 22
}`
Number
`const age = 22`
Boolean
`const isNewUser = False`
Undefined - not assigned/defined
`let result`
`let result = undefined`
Null - empty/unknown
`let data = null`
BigInt - denotes int value larger than number type can hold
Symbol - denotes a value that is unique & unchangeable