Fill the validateForm function to check that the phone number contains a number (use the isNaN function) and that the user name is less than 11 characters long. Display "Phone number is invalid" and/or "User name is invalid" in the console log if the check does not pass. Use the preventDefault function to avoid submitting the form when the inputs are invalid.

Hi there! This question is asking to write a Javascript validation function to validate user input. Assuming the input fields have the id set as “phone_number” for the phone input, and “user_name” for the User’s name, we can write the function below to do the validation as required.

Explanation:

function validateForm() {

   if isNaN(document.getElementById(“phone_number”).value) {

       document.getElementById(“phone_number”).addClass(“error”)

       console.log(“Phone number is invalid”)

   }

   if document.getElementById(“user_name”).length < 11 {

       document.getElementById(“user_name”).addClass(“error”)

       console.log(“User name is invalid”)

   }

   document.getElementById(“submit”).addEventListener(“click”, function(e) {  

       if document.getElementById(“phone_number”).hasClass("error") || document.getElementById(“user_name”).hasClass(“error”)  {

           e.preventDefault();  

       }

   });

}