example.html

<script>
ss_thank_you_message = "Thank you for signing up.";
ss_event_name        = "StreamSend Signup Form";
ss_account_id        = 1234;
</script>
<style>

/* class for all fields with errors */
.field-error {background: red;}

/* class for error message */
.streamsend-error {color: red; }

/* id for the streamsend form */
#streamsend_form { }

/* id for the streamsend form success message */
#streamsend_form_success {color: green; } 

/* id for the email address input */
#email_address { }

/* id for the submit button */
#streamsend-submit { }

</style>

<form id="streamsend_form" name="streamsend_form" method="post">
    <div>
        <label>Email</label>
        <input placeholder="Email" type="email" id="email_address" name="email_address" tabindex="1" autofocus />
        <button type="submit" name="submit" id="streamsend-submit" tabindex="10">Send</button>
        <div id="streamsend-error" class="streamsend-error"></div>
    </div>
</form>
<div id="streamsend_form_success"></div>

<script src="//cdn.statstrk01.com/assets/javascripts/sdk2.js" async></script>
<script>
document.getElementById('streamsend_form').addEventListener('submit', function(event) {
	StreamSendSubmit(event.target);
	event.preventDefault();
	function StreamSendSubmit(form) {
	    if (validEmail(form)) {
		return false;
	    } else {
		    window._ssstats = window._ssstats || [];
		    _ssstats.push([
			'configure', {
			    accountId: ss_account_id
			}
		    ]);
		    _ssstats.push(['identify', form.email_address.value]);
		    _ssstats.push(['publish', ss_event_name]);

	       document.getElementById('streamsend_form').innerHTML = "";
	       document.getElementById('streamsend_form_success').innerHTML = ss_thank_you_message;
	       return false;
	    }
	}
	function validEmail(form)   
	{  
	 if (/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/.test(form.email_address.value))  
	  {  
	    document.getElementById('email_address').className = "";
	    document.getElementById('streamsend-error').innerHTML = '';
	    return false;
	  }
	  else {
	    document.getElementById('email_address').className = "field-error";
	    document.getElementById('streamsend-error').innerHTML = "Please enter a valid email address";
	    return true;
	  }
	}  
}, false);
</script>