Validating an 11-digit string input in JavaScript

I'm trying to make sure the input in a particular field is just an 11 digit number, however my if condition does not seem to be working:

Javascript:

<script>
    function check() {
var x = document.forms["myform"]["mobile"].value;
if (!/^\d{11}$/.test(x)) {

  myform.action="gender.html";
else { 
myform.action="mobilerror.html"
}
}
</script>

And the HTML is:

<form id="myform"  onsubmit="check();" >
        <input class="input" type="text" name="mobile" required="required"
   oninvalid="this.setCustomValidity('Number is empty')" oninput="setCustomValidity('')" ></input>
    </form>

Please help!