Before we can interact with HTML elements on a page, those elements need to have been loaded: we can only change them once they’re already there. In the old days of JavaScript, the only reliable way to do this was to wait for the entire page (including images) to finish loading before we ran any scripts.
Fortunately for us, jQuery has a very cool built-in event that executes our magic as soon as possible. Because of this, our pages and applications appear to load much faster to the end user:
$(document).ready(function() {
alert("TEST");
});
The important bits here (highlighted in bold) say, “When our document is ready, run our function.” This is one of the most common snippets of jQuery you’re likely to see. It’s usually a good idea to do a simple alert test like this to ensure you’ve properly included the jQuery library—and that nothing funny is going on.
