Trying to add a "check availability" option to my register form

I am trying to add a "check availability" option for the username in my register form.

I have tried using the button tag, but my HTML5 validation prevents the code from being run. Here's my form, oversimplified:

<input type='text' required>  
<!-- The button !--> 
<button onclick='isAvailable()'>Check Availability </button>
<input type='password' required>
<input type='email' required>

If the user does not enter a username, password, and (valid) email, then the browser returns an error when the button is clicked.

I have tried using a link instead, but I don't know how to run my PHP code through it. Can anyb开发者_高级运维ody help?

Add a return false; to the onclick event.

<button onclick='isAvailable(); return false;'>Check Availability</button>

And use an Ajax call for the isAvailable() function to check the availability.

Try to use jQuery library. You can use this: http://api.jquery.com/jQuery.get/ to get return from your url: http://example.com/checknick.php?&nick=...