Dynamically resize iframe

This can be done using pure CSS as below:

iframe {
  height: 300px;
  width: 300px;
  resize: both;
  overflow: auto;
}

Set the height and width to the minimum size you want, it only seems to grow, not shrink.

You can do this in about 30 characters. Change:

$(".iframe-class").removeClass("iframe-class-resize")

to:

$(".iframe-class").removeClass("iframe-class-resize").css({ width : '', height : '' })

This will reset the width/height you applied to the element. When you use .css() you add whatever you pass-in to the style attribute of the element. When you pass a blank value, jQuery removes that property from the style attribute of the element.

Here is an updated fiddle: http://jsfiddle.net/TBJ83/3/

EDIT

OK, here's something tweaked for performance (and just some other ways to do things):

$(function () {

    //setup these vars only once since they are static
    var $myIFRAME   = $(".iframe-class"),//unless this collection of elements changes over time, you only need to select them once
        ogWidth     = 700,
        ogHeight    = 600,
        ogRatio     = ogWidth / ogHeight,
        windowWidth = 0,//store windowWidth here, this is just a different way to store this data
        resizeTimer = null;

    function setIFrameSize() {
        if (windowWidth < 480) {

            var parentDivWidth = $myIFRAME.parent().width(),//be aware this will still only get the height of the first element in this set of elements, you'll have to loop over them if you want to support more than one iframe on a page
                newHeight      = (parentDivWidth / ogRatio);

            $myIFRAME.addClass("iframe-class-resize").css({ height : newHeight, width : parentDivWidth });
        } else {
            $myIFRAME.removeClass("iframe-class-resize").css({ width : '', height : '' });
        }
    }

    $(window).resize(function () {

        //only run this once per resize event, if a user drags the window to a different size, this will wait until they finish, then run the resize function
        //this way you don't blow up someone's browser with your resize function running hundreds of times a second
        clearTimeout(resizeTimer);
        resizeTimer = setTimeout(function () {
            //make sure to update windowWidth before calling resize function
            windowWidth = $(window).width();

            setIFrameSize();

        }, 75);

    }).trigger("click");//run this once initially, just a different way to initialize
});