use of contains in javascript code example

Example 1: check if word is in string javascript

var str = "Hello world, welcome to the universe.";
var n = str.includes("world");

Example 2: javascript string includes

const s = 'I am going to become a FULL STACK JS Dev with Coderslang';

console.log(s.includes('FULL STACK'));     // true
console.log(s.includes('cheeseburger'));   // false