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How does javascript execute code + call stack

JavaScript Execution Context {} --> Global Execution Context --> It refers with (this) variable

Browser Global Execution context different from node js, bun and deno

In browser this value comes as WINDOW

JavaScript is a Single threaded

There are two types of execution context in javascript:-

i) Global Execution Context ii) Function Execution Context iii) Eval Execution Context

{ } ==> Memory Creation Phase / Creation Phase ==> Execution Phase --> + - / *

let val1 = 10
let val2 = 5
function addNum(num1, num2){
    let total = num 1 + num 2
    return total
}
let result1 = addNum(val1, val2)
let result2 = addNum(18,2)

1st Step ==> Global Execution --> this

2nd Step ==> Memory Phase In this step all variable are collected and assign with that variable as UNDEFINED

val1 -> Undefined val2 -> Undefined addNum -> Defination result1 -> Undefined result2 -> Undefined

3rd Step ==> Execution Phase val1 -> 10 val2 -> 5 addNum -> new variable envrionment + Execution Thread

Jitni bar bhi ye functions execute hote hai utni bar ek naya box create hota hai jisko bolte hai NEW EXECUTIONAL CONTEXT => new variable environment + excecution thread