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Posts Tagged ‘second’

Creating dialogs on demand

August 7th, 2009

In a previous article, I explained how to load a page into a dialog. The article focused on a simple solution to keep it easy to understand. However, that simplicity does come with a drawback; the page contents are loaded immediately after the document is ready, even if the user never opens the dialog. In this article, I’ll show how to load the page on demand while still only making a single request regardless of how many times the user opens the dialog.

On-demand page loading

In order to create the dialog on the first click, we’ll take advantage of jQuery’s .one() event binding method.one() binds a handler to an event, but the handler is only ever run once. Immediately after the handler runs it unbinds itself, preventing further execution. We’ll adapt the example from the previous article to take advantage of .one():

$(document).ready(function() {
	$('#page-help').each(function() {
		var $dialog = $('<div></div>');
		var $link = $(this).one('click', function() {
			$dialog
				.load($link.attr('href'))
				.dialog({
					title: $link.attr('title'),
					width: 500,
					height: 300
				});

			$link.click(function() {
				$dialog.dialog('open');

				return false;
			});

			return false;
		});
	});
});

Adding the final touch

Now that we’ve got our dialogs loading on demand, we need to account for network latency, slow connections, etc. Previously we were loading the page contents before the user ever saw the dialog, so any delay was hidden. A simple solution for this is to just show a loading image inside the dialog until the page contents are loaded. We’ll load this image immediately on document ready to make sure that it’s ready for use when the user clicks the link to open the dialog. Loading images are generally very small in terms of file size and they can be cached by the user, so the overhead of loading the image up-front is negligible.

$(document).ready(function() {
	var $loading = $('<img src="loading.gif" alt="loading">');

	$('#page-help').each(function() {
		var $dialog = $('<div></div>')
			.append($loading.clone());
		var $link = $(this).one('click', function() {
			$dialog
				.load($link.attr('href'))
				.dialog({
					title: $link.attr('title'),
					width: 500,
					height: 300
				});

			$link.click(function() {
				$dialog.dialog('open');

				return false;
			});

			return false;
		});
	});
});

View this example in a new window

jQuery UI - Dialog , , , , ,

Basic usage of the jQuery UI dialog

April 8th, 2009

The jQuery UI dialog, like many jQuery UI plugins, is extremely easy to get started with but has a few areas that causes new users some trouble.  One of the most commonly asked questions on the jquery-ui list is “Why does my dialog only open once?”  In this article I’ll explain the problem these users are running into and how to get your dialogs to show each and every time.

Problem:

All jQuery UI plugins maintain state, such as the current option values, whether the plugin is enabled or disabled, which plugins have been initialized on the element, etc.  This state persists from the time the plugin is instantiated on the element until it is destroyed, either explicitly by the user calling .pluginName('destroy') or by removing the element (or one of its ancestors) via .remove().  Because of this state management, you cannot instantiate the same plugin on an element multiple times, unless you destroy the plugin instance first.

The problem that users often encounter with dialogs is that they try to instantiate a new dialog every time the user performs some action (generally clicking a link or a button).  This is an understandable mistake because at first glance it seems like calling .dialog() on an element is what causes the dialog to open.  In reality what is happening is that a new dialog instance is being created and then that instance is being opened immediately after instantiation.  The reason that the dialog opens is because dialogs have an autoOpen option, which defaults to true.  So when a user calls .dialog() on an element twice, the second call is ignored because the dialog has already been instantiated on that element.

Solution:

The simple solution to this problem is to instantiate the dialog with autoOpen set to false and then call .dialog('open') in the event handler.

$(document).ready(function() {
	var $dialog = $('<div></div>')
		.html('This dialog will show every time!')
		.dialog({
			autoOpen: false,
			title: 'Basic Dialog'
		});

	$('#opener').click(function() {
		$dialog.dialog('open');
		// prevent the default action, e.g., following a link
		return false;
	});
});

View this example in a new window

jQuery UI - Dialog , , , , , ,