jQuery Simple Example

HTML

<script src="//www.addressfinder.co.nz/assets/v2/widget.js"></script>
<label for="search_field">Input</label>
<input type='text' class='input_field' />
<button type="button" class="btnTest">
Test
</button>
<br/>
<div class="test_result">
Not Tested
</div>

CSS

body {
    padding: 40px;
}

label {
    font-weight: bold;
}

input[type=text] {
    width: 20em
}
.test_result {
  font-size:4em;
}

JavaScript

$(document).ready(function() {
var input = $('.input_field');
var result = $('.test_result');
        var regExpression = /\b[a-zA-Z0-9\u00C0-\u017F._%+-]+@[a-zA-Z0-9\u00C0-\u017F.-]+\.[a-zA-Z]{2,}\b/;
    
			$('.btnTest').click(function(){
          var isValid = regExpression.test(input.val());
          if (isValid)
              result.html('<span style="color:green;">This email is valid</span>');
           else
              result.html('<span style="color:red;">This email is not valid</span>');

			});

});