Closure & IIFE

A. CLOSURES

• intro:
• A closure is a fundamental concept in JavaScript that allows functions to "remember" and access their lexical scope even when they're executed outside that scope
• Function which returns anothor function
  
• get retuned function from closure
• invoke retuned function

• 3 steps: closure maintains the state of return functions.

• run the closure with arg1 and get retuned function1 from closure.

• Run the closure again with agr2 and get another retuned function2.
• run the retuned function1.

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B.IIFEs - Immendiately invoked Function Execution

• which function get executed Immendiately.

//1. Normal Function
function(){     console.log("hello");  }

//2. IIFEs
( function(){    console.log("hello");  } )();

//3. IIFEs with Arg
( function(arg){     console.log(arg);  } )("hello2");

• IIEFs have there own local scope:

• using global scoped obj in IIEFs scope:

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C. Extra : Built-in mehods and properties

1. arguments

• technically arguments are object [check above output {}], but act as array.

console.log(arguments)

console.log(arguments[0])
console.log(arguments[3]) // undefined

console.log(arguments.length) //2

2. function name and arg length

msg.name //message whuich is fn name
msg.length // 2

• name of anonymous function

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cheatsheet