JavaScript Arrow Function

Arrow functions were introduced with ES6 for shorter function syntax

Default Parameters in JavaScript

The Default Parameter allows formal parameters to be initalize with default values if no value or undefined is passed

Example 1 - ES6

function sum(x,y=0)
{
	return x+y;
}
sum(5,4); // Output : 9
sum(4); //Output : 4

Example 2 - ES5

function sum(x,y=0)
{
	y=( typeof y !==undefined) ? y:0;
	return x+y;
}
sum(5,5); // Output : 10
sum(6); //Output : 6