Rest parameters :

• The function that accepts an unspecified number of parameters ..
• It accepts an unknown number of parameters.
• The data is stored in the form of an array. We can iterate through any loop
• With the help of 3 dots (...).

Syntax: ...parameter

function addition (num1, num2, ...num){
	var sum = num1+num2;
	for ( var v  of num){
		sum = sum + v ;
	}
	console.log(sum);
}
addition(1,2,3 ) \\\\first 2 arguments are reserved and remaining reserved for rest variable..
addition(1,2,3 ,5)
addition(1,2,3 5,7)

Note : Every function contains a default object, which is called an argument; you can use it. It stores the arguments. Accessing a specific element through an index: Arguments [0] Length: it returns the length of objects. Ex: console.log(arguments);

• Rest parameters are always at the end only otherwise it will throw an error.

function dis(para1,  ...rest, para3 ){ } // error.
function dis(para1, para3, ...rest){ } // ok

Spread operator :

• It takes an iterable object and expands or separates each element.
• It is introduced in the ES6 version.

arra = [10,55,43,26];
console.log(...arra) //10 55 43 26

Example _2 :

var name = "Shivaji";
console.log(name); // without spread operator
console.log(...name); // with spread operator
//Output :
Shivaji
S h i v a j i