Function

Function
Function is a block of code designed to perform a specific task. It executes only when it is called (invoked).

Syntax

function functionName() {
// Code to execute
}

• Code reusable
• Declare code once,use it whenever we want
• Call the function to execute the code

*call Function *

function sampleFun(){
    console.log(2+3);
}
sampleFun()

Output:5

Function Parameter
Parameter- It is a variable declared in a function definition that receives the values passed to the function when it is called.
Argument- It is the value supplied to a function's parameter during a function call.These values are received by the function's parameter.

function sampleFun(a,b){
    console.log(a+b);
}
sampleFun(10,20)

Output:30

Function Return
Used to end function and send value back to the place where the function was called.

function sampleFun(a,b){
    return a+b;
}
var x=sampleFun(10,20)
console.log(x)
// console.log(sampleFun(10,20))

Output:30

Anonymous Function

- Function without a name
- Function is stored in a variable

var sampleFun=function(){
    console.log("Hello World");
}
sampleFun()

Output:Hello World

Callback Function
Function passed as an argument to another function ,which is called after a specific task is completed

 function mainFun(callback){
        console.log("main function executed");
         callback()
    }
    //  console.log(callback)

    function callback(){
        console.log("callback function executed");
    }
    mainFun(callback)
    // callback()

Output:main function executed
callback function executed

Self-invoking Function
OR IIFE-Immediately Invoking Function Expression
Function that executes automatically as soon as it is defined or created

(function() {
        console.log("Self-invoking function executed");
    })();

Output:Self-invoking function executed

Arrow Function
- Arrow Functions allow a shorter syntax for function expressions
- Can skip the function keyword, the return keyword, and the curly brackets

    var sampleFun = () => {
        console.log("Arrow function executed");
    };
    sampleFun();

Output:Arrow function executed

 const multiply = (a, b) => a * b;
    console.log(multiply(5, 5));

Output:25