Let's take an example that shows the differences between call-by-reference and call-by-string. The function setVisibility() sets the visibility of a passed-by-string element:

function docjslib_setVisibility(id, flag) {
  if (NS4) {
    var str = (flag) ? 'show' : 'hide';
    eval("document." + id).visibility = str;
  }
  else {
    var str = (flag) ? 'visible' : 'hidden';
    eval("document.all." + id).style.visibility = str;
  }
}

The following function sets the visibility of elements that are passed by reference (objects):

function docjslib_setElementVisibility(id, flag) {
  if (NS4) {
    var str = (flag) ? 'show' : 'hide';
    eval(id).visibility = str;
  }
  else {
    var str = (flag) ? 'visible' : 'hidden';
    eval(id).style.visibility = str;
  }
}

Learn more about DOCJSLIB 4.0 in Column 33, DOCJSLIB Version 4.0: Scrollers, Watermarks, and Games

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