html - oncheck listener for checkbox in javascript

Question

I have code like this at the bottom of my form.

<p>
  <input type="checkbox" id="agreed">
  I agree to keep my Username and Password confidential and uphold 
  the integrity of this pharmacy
</p>
<input type="submit" id="submit" disabled class="formbutton button-primary" value="Go">

I want this a listener in JavaScript to be able to enable the submit button. I know it might be wrong or something but my JavaScript looks sort of like this

function track() {
    if ( document.getElementById("agreed").checked==true ) {
        document.getElementById("submit").removeAttribute("disabled");
    } else {
        document.getElementById("agreed").checked==false
    }
};

Answer 1

You can do this for the input:

<input type='checkbox' onchange='handleChange(this);'>Checkbox

And this for enabling the button:

function handleChange(checkbox) {
    if(checkbox.checked == true){
        document.getElementById("submit").removeAttribute("disabled");
    }else{
        document.getElementById("submit").setAttribute("disabled", "disabled");
   }
}