check matches array javascript code example

Example 1: find string in array javascript

var myarr = ["I", "like", "turtles"];
var arraycontainsturtles = (myarr.indexOf("turtles") > -1);

Example 2: javascript find matching elements in two arrays

let firstArray = ["One", "Two", "Three", "Four", "Five"];
let secondArray = ["Three", "Four"];

let map = {};
firstArray.forEach(i => map[i] = false);
secondArray.forEach(i => map[i] === false && (map[i] = true));
let jsonArray = Object.keys(map).map(k => ({ name: k, matched: map[k] }));