if element in list check js code example

Example 1: how to check if item is in list js

var myList=["a", "b", "c"];
mylist.includes("d")//returns true or false

Example 2: check items in array javascript

function checkAllEven(arr) {
  return arr.every(function(x){
	 return	x % 2 === 0
	})
}

//using "every" to check every item in array.