• Function is a store of steps that you take to perform certain action.

Parameter and Argument

Parameter

• Parameter is defined when defining a function .
• Parameter are the placeholder.

Argument

• The value that pass when you calling a function.
• Argument are the real value.

Default Parameter

• The default parameter is a way to set default values for function parameters a value is no passed in

function multiply(a, b = 1) {
  return a * b;
}

console.log(multiply(5, 2));
// expected output: 10

console.log(multiply(5));
// expected output: 5

Different Types of function

Function Declaration

function add(numA, numB){
return numA + numB;
}

Function Expression

• It can stored in a variable.

const addNumber=function add(numA, numB){
return numA + numB;
}

Anonymous Function Expression

• Do not need function names

const addNumber=function (numA, numB){
return numA + numB;
}

Arrow Function Expression

• No need to write function key;

const addNumber=(numA, numB)=>{
return numA + numB;
}

const addNumber=(numA, numB)=>
 numA + numB;