check if string contains substring javascript

var str = "We got a poop cleanup on isle 4.";
if(str.indexOf("poop") !== -1){
	alert("Not again");
}
//use indexOf (it returns position of substring or -1 if not found)var str = "Hello world, welcome to the universe.";

var n = str.includes("world");
 const string = "foo";
const substring = "oo";

console.log(string.includes(substring));var str = "Hello world, welcome to the universe.";
var n = str.includes("world");var string = "foo";
var substring = "oo";

console.log(string.indexOf(substring) !== -1);var string = "foo",
    substring = "oo";

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