const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.includes("Mango");

const ratings = [1,2,3,4,5];
let result = ratings.includes(4);
console.log(result); // true
result = ratings.includes(6);
console.log(result); // false

// check if an array INCLUDES a certain value
//array for includes()
let numbers = [1, 2, 3, 4, 5]
// either true or false
numbers.includes(2) // returns true, the numbers array contains the number 2
numbers.includes(6) // returns false, the numbers array DOESNT contain the number 6

let isInArray = arr.includes(valueToFind[, fromIndex])
// arr - array we're inspecting
// valueToFind - value we're looking for
// fromIndex - index from which the seach will start (defaults to 0 if left out)
// isInArray - boolean value which tells us if arr contains valueToFind

var array = [1, 3], prizes = [[1, 3], [1, 4]], includes = prizes.some(a => array.every((v, i) => v === a[i]));
console.log(includes);

array.includes('element that need to be checked') //returns true or false 

var contains = function(needle) { // Per spec, the way to identify NaN is that it is not equal to itself var findNaN = needle !== needle; var indexOf; if(!findNaN && typeof Array.prototype.indexOf === 'function') { indexOf = Array.prototype.indexOf; } else { indexOf = function(needle) { var i = -1, index = -1; for(i = 0; i < this.length; i++) { var item = this[i]; if((findNaN && item !== item) || item === needle) { index = i; break; } } return index; }; } return indexOf.call(this, needle) > -1;
};