JavaScript 1

Data Types in JS

Primitive Types

• Number
• Boolean
• String
• Undefined
• Null
• Bigint
• Symbol

NaN in JS

The NaN global property is a value representing Not-A-Number.

Operator Precendence

This is the general order of solving an expression.

1. ()
2. **
3. *,/,%
4. +,-

Note:- power wale same operator jayada rahne par right to left solve karenge sirf power wale ko, baki ko left to right as u studied in c.

% modulo operator

= assingment oprerator

Identifier Rules

All JavaScript variables must be identified with unique names (identifiers).

• Names can contain letters, digits, underscores, and dollar signs. (no space)

• Names must begin with a letter.

• Names can also begin with $ and _ .

• Names are case sensitive (y and Y are different variables).

• Reserved words (like JavaScript keywords) CANNOT be used as names.

let keyword

Syntax of declaring variables.

const keyword

values of constants can't be changed with re-assignment & they can't be re-declared.

var keyword

Old Syntax of writing variables. //pahale use hota tha, 2015 me let aya to ab use nahi hota ha.

Boolean in JS

Boolean represents a truth value -> true or false I yes or no.  //case sensetive true,false,thik se likho😢

Javascript ke andar ham variable ka type kabhi bhi change kar sakte hai, but c++,java me nahi

What is TypeScript?

Static Typed, where JS is dynamic typed.   //mtb eska variable ka type change nahi kar sakte hai,typescript javascript ka bhai.........

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