check if string is already in array javascript 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: see if array contains array javascript

const found = arr1.some(r=> arr2.indexOf(r) >= 0)

Example 3: javascript check if array is in array

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

console.log(includes);

Example 4: check if array does not contain string js

function checkInput(input, words) {
 return words.some(word => new RegExp(word, "i").test(input));
}

console.log(checkInput('"Definitely," he said in a matter-of-fact tone.', 
["matter", "definitely"]));