how to find the variable that contains something in javascript code example

Example 1: javascript contains substring

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)

Example 2: .includes( string

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