How to grey out checkbox unless radio button is selected?

checkbox, css, javascript, radio-button

Solution

I've noticed that you don't specify whether or not you can use jQuery. If that's an option, please see one of the other posts as I highly recommend it.

If you cannot use jquery then try the following:

<script>
  function setFries(){
    var el = document.getElementById("burger");
    if(el.checked)
      document.getElementById("fries").disabled = false;
    else
     document.getElementById("fries").disabled = true;    
  }  
</script>


<div><input type="radio" name="o1" id="burger" onchange="setFries();"/>Burger</div>
<div id="yesFries"><input type="checkbox" name="e1" id="fries" disabled="disabled"/>Fries with that?</div>
<div><input type="radio" name="o1" id="pizza" onchange="setFries();"/>Pizza</div>
<div><input type="radio" name="o1" id="hotdog" onchange="setFries();"/>Hot Dog</div>​

Simple example on jsFiddle

Problem

Original source