How to check whether a string contains a substring in JavaScript?

There are a few ways to check if a string contains a substring, one of these ways is using regular expressions (regex), and a different one is using the method includes which was introduced in ECMAScript 6.ECMAScript 6 introduced String.prototype.includes: const string = "foo"; const substring = "oo"; console.log(string.includes(substring)); // trueString.prototype.includes is case-sensitive and is not supported by Internet Explorer without a polyfill.In ECMAScript 5 or older environments, use String.prototype.indexOf, which returns -1 when a substring cannot be found:

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