javascript or operator in function arg code example

Example 1: javascript function variable arguments

function foo() {
  for (var i = 0; i < arguments.length; i++) {
    console.log(arguments[i]);
  }
}

foo(1,2,3);
//1
//2
//3

Example 2: the rest operator javascript

function sum(...numbers) {
	return numbers.reduce((accumulator, current) => {
		return accumulator += current;
	});
};
 
sum(1,2) // 3
sum(1,2,3,4,5) // 15