.. _selectors:
.. index:: selector, DOM, HTML
=========
Selectors
=========
CasperJS makes a heavy use of selectors in order to work with the `DOM `_, and can transparently use either `CSS3 `_ or `XPath `_ expressions.
All the examples below are based on this HTML code:
.. code-block:: html
My page
Hello
.. index:: CSS, CSS3
CSS3
----
By default, CasperJS accepts `CSS3 selector strings `_ to check for elements within the DOM.
To check if the ```` element exists in the example page, you can use::
var casper = require('casper').create();
casper.start('http://domain.tld/page.html', function() {
if (this.exists('h1.page-title')) {
this.echo('the heading exists');
}
});
casper.run();
Or if you're using the :doc:`testing framework `::
casper.test.begin('The heading exists', 1, function suite(test) {
casper.start('http://domain.tld/page.html', function() {
test.assertExists('h1.page-title');
}).run(function() {
test.done();
});
});
Some other convenient testing methods are relying on selectors::
casper.test.begin('Page content tests', 3, function suite(test) {
casper.start('http://domain.tld/page.html', function() {
test.assertExists('h1.page-title');
test.assertSelectorHasText('h1.page-title', 'Hello');
test.assertVisible('footer');
}).run(function() {
test.done();
});
});
.. index:: XPath
XPath
-----
.. versionadded:: 0.6.8
You can alternatively use `XPath expressions `_ instead::
casper.start('http://domain.tld/page.html', function() {
this.test.assertExists({
type: 'xpath',
path: '//*[@class="plop"]'
}, 'the element exists');
});
To ease the use and reading of XPath expressions, a ``selectXPath`` helper is available from the ``casper`` module::
var x = require('casper').selectXPath;
casper.start('http://domain.tld/page.html', function() {
this.test.assertExists(x('//*[@id="plop"]'), 'the element exists');
});
.. warning::
The only limitation of XPath use in CasperJS is in the :ref:`casper.fill() ` method when you want to fill **file fields**; PhantomJS natively only allows the use of CSS3 selectors in its `uploadFile method `_, hence this limitation.