Firefox Error in parsing value for 'height'. Declaration dropped

I have developed Java Script to find the height of columns height and make it match for all columns in the web page but I was getting an  error “Error in parsing value for 'height'.  Declaration dropped” in the Firefox but in IE it is working fine without issue, then we I cross checked the script I found the issue I forget to define the unit of measure, so I just added the unit of measure and this issue resolved, following the old code and new code.

Old Code

   function msetcontainer() {

        if (document.getElementById) {

            var windowHeight = getWindowHeight();

            if (windowHeight > 0) {

                var contentHeight =

        document.getElementById('rightcol').offsetHeight;

                var contentID = document.getElementById('rightcol');

                var LeftcontentHeight =

        document.getElementById('leftcol').offsetHeight;

                var LeftcontentID = document.getElementById('leftcol');

                if (LeftcontentHeight != contentHeight) {

                    contentID.style.height = LeftcontentHeight;

                }

            }

        }

    }

New Code

   function msetcontainer() {

        if (document.getElementById) {

            var windowHeight = getWindowHeight();

            if (windowHeight > 0) {

                var contentHeight =

        document.getElementById('rightcol').offsetHeight;

                var contentID = document.getElementById('rightcol');

                var LeftcontentHeight =

        document.getElementById('leftcol').offsetHeight;

                var LeftcontentID = document.getElementById('leftcol');

                if (LeftcontentHeight != contentHeight) {

             //there was issue with firefox becasue i forget to add + 'px'

                    contentID.style.height = LeftcontentHeight + 'px' ;

                }

            }

        }

    }