getBoundingClientRect in each: undefined is not a function

So I am trying to call some functions when fullscreen sections are in the viewport. Let's say I have 7 sections, then I want something to happen when a certain section is inside the viewport (I have a function that snaps the sections into the viewport so there can never be multiple sections in the viewport, but I am trying to find out which section is visible in the viewport).

Here is a fiddle: http://jsfiddle.net/h7Hb7/2/

function isInViewport() {
    $("section").each(function () {
        var $this = $(this),
            wHeight = $(window).height(),
            rect = $this.getBoundingClientRect(); // Error in console

        // Borrowed from http://stackoverflow.com/a/7557433/5628
        if (rect.top >= 0 && rect.bottom <= wHeight) {
            console.log($this.attr("id") + "in viewport");
        }
    });
}

$(window).scroll(function () {
    // Other functions are called inside the setTimeout function, can't remove
    clearTimeout($.data(this, "scrollTimer"));
    $.data(this, "scrollTimer", setTimeout(function () {
        isInViewport();
    }, 1200));
});

I don't know where to start looking but I am guessing it's to do with the each function. Is it the each function that poses a problem? It can't be a CSS issue, because the problem occurs on scroll when the CSS has already loaded.

jQuery object doesn't have getBoundingClientRect method, you should get the HTMLElement object and then call the method or:

this.getBoundingClientRect();

As a suggestion, if using a plugin is an option, you can consider using the jquery.inview plugin.