It would be an understatement to say that jQuery is useless when it comes to DOM parsing and AJAX queries. This is indeed a nice and widely used library and anyone who tried to scrape data from HTML with jQuery once may have a lot of regrets while returning to XPath*.
So, in order to make your scraping jobs an agreable moment, artoo.js injects jQuery within the page you are browsing.
But he does it carefully, ensuring that the injection of foreign code won’t trouble the execution of the page you are scraping.
The logic followed by the jQuery injection is the following:
- If jQuery is present on the page in a correct version (superior to 2 by default), nothing is done.
- If jQuery is not present and if
$is not used by some other library, a suitable version of jQuery is injected.- Finally, if jQuery is present in a wrong version or if
$is used by another library, jQuery will be injected but won’t override the page’s$. jQuery is then be available throughartoo.$.
If you find exhausting to use artoo.$ in pages where artoo thinks he should not override another $ variable and if you know for sure that reassigning it won’t cause trouble, you are obviously free to do so.
var $ = artoo.$;
You can also force jQuery to override the present $ variable in the library’s settings.
Finally, if you prefer another jQuery version, you can also configure it in the same settings.
In order to be able to trigger complex DOM events as well as a human would, artoo encapsulates the jquery.simulate plugin.
It is commonly used to perform functionnal testing and ensure that interfaces are working correctly. But scrapers know it can be useful otherwise…
Every artoo.js’ scraping methods also comes packed as a jQuery plugin.
artoo.scrape('.class', params);
// equals
$('.class').scrape(params);
Knowing that you may not be able to access easily jQuery through the global $, artoo.js gives access to his internal jQuery instance in some of his methods callbacks. This is for instance the case for the artoo.scrape method.
Example
// The callbacks take a first argument being a reference to artoo.$
artoo.scrape('ul > li', function($) {
return $(this).attr('data-name');
});
* Rejoice, XPath users, for $x exists in Chrome and Chromium if you ever need it.