JSFiddle - React, Tailwind, and code Playground

JavaScript

var stringy = 'xxxx@yahoo.com';
var stringy2 = 'xxxx@notyahoo.com';
if (stringy.match(/^[a-z0-9_.\-]+@(yahoo|gmail|deadforce)\.com$/)) {
    console.log('Matched');
} else {
    console.log('No Match');
}
if (stringy2.match(/^[a-z0-9_.\-]+@(yahoo|gmail|deadforce)\.com$/)) {
    console.log('Match2');
} else {
    console.log('No Match2');
}