Kenyan Regex Number Formatting Function for Javascript

Here is how to…

var regEx = /^(?:254|\+254|0)?(7(?:(?:[129][0-9])|(?:0[0-8])|(4[0-1]))[0-9]{6})$/;
var phonenumber = '+254721123456'
if (phonenumber.match(regEx)) {
    console.log('true');
} else {
    console.log('false');
}

Happy Coding!