js check if string contains string code example

Example 1: check if string contains javascript

var str = "Hello world, welcome to the universe.";

var n = str.includes("world");

Example 2: check for substring javascript

const string = "javascript";
const substring = "script";

console.log(string.includes(substring));  //true

Example 3: js string contains

var string = "foo";
var substring = "oo";

console.log(string.indexOf(substring) !== -1);