1var string = "foo",
2    substring = "oo";
3
4console.log(string.includes(substring));

1const string = "foo";
2const substring = "oo";
3
4console.log(string.includes(substring));

1s = "Hello world";
2console.log(s.includes("world"));

1var email = "grepper@gmail.com";
2if(email.includes("@")){
3  console.log("Email is valid");
4}
5else{
6  console.log("Email is not valid");
7}
8// includes return boolean, if your string found => true else => false

1var str = "We got a poop cleanup on isle 4.";
2if(str.indexOf("poop") !== -1){
3	alert("Not again");
4}
5//use indexOf (it returns position of substring or -1 if not found)

1var string = "foo",
2var substring = "oo";
3
4console.log(string.includes(substring));