Document Ready Function

To prevent jQuery code from running before the document is completely loaded, all jQuery functions should be placed within the $(document).ready function. For example:

$(document).ready(function(){   
// Do something on document ready. 
});

If you prefer, you can use a shortened version of the $(document).ready function instead. For example:

$(function() {
// do something on document ready
});

All scripts residing inside of the $(document).ready function will load as soon as the DOM is loaded and before the page contents are loaded.