JAVASCRIPT

javascript element in array

var letters = ["A", "B", "C", "D"];

var result = letters.includes("A");
// result will be TRUE or FALSE

javascript element in array

var fruits = ["Banana", "Orange", "Apple", "Mango"];

var n = fruits.includes("Mango");

js in_array

var a = [1, 2, 3];
a.includes(2); // true 
a.includes(4); // false