Check if the phone number input contains only digits and it has minimum length
Phone Number Validation using JavaScript.
Recommended For You
JavaScript Tutorial – Password Validation, Check length and confirm password
JavaScript Tutorial – Email Validation, Check email address format
JavaScript Tutorial – Select List Validation, Check if any option selected
Show multiple error messages in one alert box in JavaScript
JavaScript Tutorial : How to perform addition operation and get result using javascript 
JavaScript Tutorial : How to show system date in a webpage using javascript