JavaScript problem in a WordPress PAGE

Question

I did a simple HTML page which has JavaScript as following:

<script>
  function myFunction() {
    var y = document.querySelector('input[name="mum1"]:checked').value;  
    var z = document.querySelector('input[name="num2"]:checked').value;
    var x = +y + +z;
    document.getElementById("total").innerHTML = x;
  }
</script>

<button onclick="myFunction()">Try it</button>

It works fine by itself. When I add it to a WordPress website(add HTML in a page). The error message comes like this:

Uncaught SyntaxError: Unexpected token 
Uncaught ReferenceError: myFunction is not defined

I guess this cause by JavaScript conflict, my WordPress website use jquery.

How to solve the problem.

Answer 1

Change

var x = +y + +z;

to

var x = Number(y) + Number(z);

Done~