Basic Form Validation

JavaScript Form Validation

HTML form validation can be done by JavaScript.

If a form field (fname) is empty, this function alerts a message, and returns false, to prevent the form from being submitted:

    
    <!DOCTYPE html>
    <html lang="en">
    <head>
        <script>

            function validate(){
                
                var username = document.getElementById("uname");
                var password = document.getElementById("pass");

                if( username.value == "" || password.value == ""){
                    alert("NO Empty fields required")
                    return false;
                }else{
                    return true;
                }
            
            }

        </script>
    </head>
    <body>

        <form onsubmit="return validate()" action="WelcomePage.html">
            <input type="text" placeholder="user name" id="uname">
            <input type="text" placeholder="password" id="pass" ><br />            
            <button>Submit</button>       
        </form>

    </body>
    </html>