Most commonly used regex, ES6

regex.js

const phoneRegx = RegExp(/^[0]?[789]\d{9}$/)
const emailRegx = RegExp( /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/)

let phoneNumber = '9999999999'
let email = '[email protected]'

console.log('PHONE REGX:= ', phoneRegx.test(phoneNumber));
console.log('EMAIL REGX:= ', emailRegx.test(email));