href does not seem to work

Question

why does the following not work. it only takes me to the index.php page and cuts off the "get" data

 <div class="wrapper">
        <form class="form-signin" method="post">       
            <h2 class="form-signin-heading">Customer Not Found</h2>
              No customer was found matching <?=$_POST['phone'];?>.<br/>
              You can create a new customer with this number, or search again<br/>
              <button
                      class="btn btn-lg btn-primary btn-block"

                      id="createCust"
              >
                     Create A New Customer
              </button>   
              <button class="btn btn-lg btn-primary btn-block" type="submit" name="login">Search Again</button>   
        </form>
    </div>
 <script type="text/javascript">
    document.getElementById("createCust").onclick = function () {
        location.href = "index.php?proc=newCust&p=<?=$_SESSION['phone'];?>";
    };
</script>

Answer 1

As @Teemu stated:

The default action for a button in a form is to submit the form. A pending server call will block changes to location.href. Define the button as type of button. –

I had the "type" as submit, changing it to type="button" solved this problem.