"Check" Multiple Checkboxes With Click & Drag?

Question

I have a table filled with checkboxes like so:

I'd like to be able to keep my mouse held down and drag to activate multiple checkboxes. I don't have the slightest clue where to start with this :/ I searched for an answer, but only found another thread of someone asking how to do it, but with no answers.

HTML:

<table>
  <tbody>
    <tr>
      <td><input type="checkbox"></td>
      <td><input type="checkbox"></td>
      <td><input type="checkbox"></td>
    </tr>
    <!-- Repeat tr 2x -->
  </tbody>
</table>

jsFiddle: https://jsfiddle.net/CSS_Apprentice/ge1zx2yg/

Also, I'd prefer to keep the <input type="checkbox"> model because reworking my system would be time consuming, but I'm open to other options if this isn't possible. Any help will be greatly appreciated!

Answer 1

<table>
  <tbody>
    <tr>
      <td><input id=1 onmouseover='check(1)' type="checkbox"></td>
      <td><input id=2 onmouseover='check(2)' type="checkbox"></td>
      <td><input id=3 onmouseover='check(3)' type="checkbox"></td>
    </tr>
    <tr>
      <td><input id=4 onmouseover='check(4)' type="checkbox"></td>
      <td><input id=5 onmouseover='check(5)' type="checkbox"></td>
      <td><input id=6 onmouseover='check(6)' type="checkbox"></td>
    </tr>
    <tr>
      <td><input id=7 onmouseover='check(7)' type="checkbox"></td>
      <td><input id=8 onmouseover='check(8)' type="checkbox"></td>
      <td><input id=9 onmouseover='check(9)' type="checkbox"></td>
    </tr>
  </tbody>
</table>

<script>
  function check(id)
  {
    if(mouseDown)
      {
        document.getElementById(id).checked = 1-document.getElementById(id).checked;
        // document.getElementById(id).checked = true;
        // ^ If you only want to turn them on, use this.
      }
  }
  
  var mouseDown = 0;
  document.body.onmousedown = function()
  { 
    ++mouseDown;
  }
  
  document.body.onmouseup = function()
  {
  --mouseDown;
  }
  // Credit to http://stackoverflow.com/questions/322378/javascript-check-if-mouse-button-down
</script>

Or, alternatively, use the code beneath to avoid IDs:

<table>
  <tbody>
    <tr>
      <td><input onmouseover='check(this)' type="checkbox"></td>
      <td><input onmouseover='check(this)' type="checkbox"></td>
      <td><input onmouseover='check(this)' type="checkbox"></td>
    </tr>
    <tr>
      <td><input onmouseover='check(this)' type="checkbox"></td>
      <td><input onmouseover='check(this)' type="checkbox"></td>
      <td><input onmouseover='check(this)' type="checkbox"></td>
    </tr>
	<tr>
      <td><input onmouseover='check(this)' type="checkbox"></td>
      <td><input onmouseover='check(this)' type="checkbox"></td>
      <td><input onmouseover='check(this)' type="checkbox"></td>
    </tr>
  </tbody>
</table>

<script>
  function check(box)
  {
    if(mouseDown)
      {
        box.checked = 1-box.checked;
		// box.checked = 1;
        // ^ If you only want to turn them on, use this.
      }
  }
  
  var mouseDown = 0;
  document.body.onmousedown = function()
  {++mouseDown;}
  document.body.onmouseup = function()
  {--mouseDown;}
  // Credit to http://stackoverflow.com/questions/322378/javascript-check-if-mouse-button-down
</script>