Validate Email Addresses With JavaScript and Regex

Very handy code to validate input on the client in the browser using JavaScript and Regular expressions

See the working demo below.

Demo: How to validate addresses with JavaScript and Regex

JavaScript

This is pretty much the standard JavaScript you'll paste into your page script block - or in a .js file if you prefer.

            
            function isEmail(elm) {
                if (elm.value == '') {
                    alert("fill in email"); return false;
                }
                var ePat = /\b[A-Za-z0-9._%-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}\b/;
                if (ePat.test(elm.value) == false) {
                    alert(elm.value + " is NOT a valid email");
                    return false;
                }else{
                         alert(elm.value + " IS A VALID email");
                    return false; 
                }
            }
        
    

CSS

Edit as necessary.

                
            body{
              font-size:2em;
              font-weight:bold;
            }
            input{
              font-size:50px;
            }
            button{
              font-size:50px;
            }
        
    

Conclusion

A few lines of JQuery is all you need to validate email addresses with javascript and regex