jQuery: testing for existence of something

Newbie alert...

I'm trying to make an educational that uses different audio players (with different ids) depending on the browser. In some cases, the div ids 开发者_Python百科will be #f-FIVE, for example, or, in other cases just #FIVE. This is not something I have a lot of control over due to the audio players.

Using jQuery, I want to use the div ids to test for which audio player is being used.

In this fiddle http://jsfiddle.net/eft84/15/, I am trying (unsuccessfully) to fade out an element using an if then structure if #f-FIVE exists. Would you be kind enough to help me spot my errors.

Here you go: http://jsfiddle.net/Paulpro/SySRb/

$('#f-FIVE').length

Will be 1 or more if there is a match (Should be exactly one since it's an id selector). If there is no match it will be 0 and evaluate to false.

With jQuery, you can check if the result of a selector is empty like this:

if ($("#f-FIVE").length) {
    // do something
}

I don't understand what the IF should do? I corrected the code below.

$(document).ready(function() {
    init();
});

function init() {
    var x = true; //#f - FIVE
    if (x === true) {
        $('#f-FIVE, #f-SIX').hide(1000);
    } else {
        return;
    }



}