check if a string is substring of another javascript code example

Example 1: string contains in javascript

const string = "foo";
const substring = "oo";

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

Example 2: 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 3: js string does not contain

"this is the string".indexOf("cake"); // -1 (does not contain)
"this string has cake".indexOf("cake"); // 16 (contains)