jQuery .css("margin-top", value) not updating in IE 8 (Standards mode)

Question

I'm building an auto-follow div that is bound to the $(window).scroll() event. Here is my JavaScript.

var alert_top = 0;
var alert_margin_top = 0;

$(function() {
  alert_top = $("#ActionBox").offset().top;
  alert_margin_top = parseInt($("#ActionBox").css("margin-top"));

  $(window).scroll(function () {
    var scroll_top = $(window).scrollTop();
    if(scroll_top > alert_top) {
      $("#ActionBox").css("margin-top", ((scroll_top-alert_top)+(alert_margin_top*2))+"px");
      console.log("Setting margin-top to "+$("#ActionBox").css("margin-top"));
    } else {
      $("#ActionBox").css("margin-top", alert_margin_top+"px");
    };
  });
});

This code assumes that there is this CSS rule in place

#ActionBox {
  margin-top: 15px;
}

And it takes an element with the id "ActionBox" (in this case a div). The div is positioned in a left aligned menu that runs down the side, so it's starting offset is approximately 200 px). The goal is to start adding to the margin-top value once the user has scrolled past the point where the div might start to disappear off the top of the browser viewport (yes I know setting it to position: fixed would do the same thing, but then it would obscure the content below the ActionBox but still in the menu).

Now the console.log shows that the event is firing every time it should and it's setting the correct value. But in some pages of my web app the div isn't redrawn. This is especially odd because in other pages (in IE) the code works as expected (and it works every time in FF, Opera and WebKit). All pages evaluate (0 errors and 0 warnings according to the W3C validator and the FireFox HTMLTidy Validator), and no JS errors are thrown (according to the IE Developer Toolbar and Firebug). One other part to this mystery, if I unselect the #ActionBox margin-top rule in the HTML Style explorer in the IE Developer Tools then the div jumps immediately back in the newly adjusted place that it should have if the scroll event had triggered a redraw. Also if I force IE8 into Quirks Mode or compatibility mode then the even triggers an update.

One More thing, it works as expected in IE7 and IE 6 (thanks to the wonderful IETester for that)

Answer 1

Try marginTop in place of margin-top, eg:

$("#ActionBox").css("marginTop", foo);

Answer 2

I'm having a problem with your script in Firefox. When I scroll down, the script continues to add a margin to the page and I never reach the bottom of the page. This occurs because the ActionBox is still part of the page elements. I posted a demo here.

• One solution would be to add a position: fixed to the CSS definition, but I see this won't work for you
• Another solution would be to position the ActionBox absolutely (to the document body) and adjust the top.
• Updated the code to fit with the solution found for others to benefit.

UPDATED:

CSS

#ActionBox {
 position: relative;
 float: right;
}

Script

var alert_top = 0;
var alert_margin_top = 0;

$(function() {
  alert_top = $("#ActionBox").offset().top;
  alert_margin_top = parseInt($("#ActionBox").css("margin-top"),10);

  $(window).scroll(function () {
    var scroll_top = $(window).scrollTop();
    if (scroll_top > alert_top) {
      $("#ActionBox").css("margin-top", ((scroll_top-alert_top)+(alert_margin_top*2)) + "px");
      console.log("Setting margin-top to " + $("#ActionBox").css("margin-top"));
    } else {
      $("#ActionBox").css("margin-top", alert_margin_top+"px");
    };
  });
});

Also it is important to add a base (10 in this case) to your parseInt(), e.g.

parseInt($("#ActionBox").css("top"),10);

Answer 3

I found the answer!

I want to acknowledge the hard work of everyone in trying to find a better way to solve this problem, unfortunately because of a series of larger constraints I am unable to select them as the "answer" (I am voting them up because you deserve points for contributing).

The specific problem I was facing was a JavaScript onScoll event that was firing but a subsequent CSS update that wasn't causing IE8 (in standards mode) to redraw. Even stranger was the fact that in some pages it was redrawing while in others (with no obvious similarity) it wasn't. The solution in the end was to add the following CSS

#ActionBox {
  position: relative;
  float: right;
}

Here is an updated pastbin showing this (I added some more style to show how I am implementing this code). The IE "edit code" then "view output" bug fudgey talked about still occurs (but it seems to be a event binding issue unique to pastbin (and similar services)

I don't know why adding "float: right" allows IE8 to complete a redraw on an event that was already firing, but for some reason it does.