There is a String.prototype.includes in ES6:
"potato".includes("to");
> true
Note that this does not work in Internet Explorer or some other old browsers with no or incomplete ES6 support. To make it work in old browsers, you may wish to use a transpiler like Babel, a shim library like es6-shim, or this polyfill from MDN:
if (!String.prototype.includes) {
String.prototype.includes = function(search, start) {
'use strict';
if (typeof start !== 'number') {
start = 0;
}
if (start + search.length > this.length) {
return false;
} else {
return this.indexOf(search, start) !== -1;
}
};
}