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Validating an email entered on a form is one of the most fundamental requirements in any mobile app. In this blog post, we are going to show you how to validate an email input field using a regular expression. This blog post is a follow-up to How to Add JavaScript Form Validation to a Mobile App post.

Validating an email input field using a regular expression is very simple. Here is the code to perform email validation.

// Read a value from the email input component.
// Apperyio() is a quick wrapper for a jQuery select
// emailInput is the name of the UI component
// It's possible to use jQuery directly as well
var emailInput = Apperyio("emailInput").val();

// Regular expression to validate email input value
var re = /^(([^()[\]\\.,;:\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,}))$/;
var test = re.test(emailInput);

// condition check part
if(test) {
    alert ("Everything is good.");
}
else {
    alert("Invalid email entered. Please try again.");
}

You can quickly add this code to any app inside a JavaScript file and reuse. Looking for more examples and how-tos? Check out YouTube channel for large number of short videos.