jQuery duplicated selector
You should cache your selector in a variable:

var $addedColors = $("#colors_added");
$addedColors.html(parseFloat($addedColors.html()) + 1);


Reason: placing selectors in variables is recommended, since overusing selectors can result in poor performance.

Everytime you would call a function on $("#colors_added"), the whole DOM has to be parsed by the browser. This is not the case when you store it in a variable.

Also, it's a general principle to not repeat yourself in code, also called the DRY principle (as mentioned by Peter Rader in the comments).