I'm developing a site where the user will choose a point on an OpenLayers map in a dialog box (displayed using jQuery UI) which will then do something on the rest of the page based on the point chosen on the map. The user can also call up the dialog at any time to pick a new point.
I've got the map dialog and passback of lat/long working just fine, but my question comes to page load optimization. I originally had all of my map code right in my $(document).ready() function with my OpenLayers.js call right in the <head> of the page. To try and improve things a bit, I moved the map code into its own .js file and put the links (<script> tags) to both at the very bottom of the <body> tag. It seems slightly better, though I do notice the navigational elements for the map (zoom controls and such) flash briefly on the screen, I presume before the stylesheet tells them to hide. Is there any way I could force the map to only load when the dialog is about to be displayed, as I feel that a slightly delay there would be more ideal than a delay in the main interface loading (subtle as that might be)? And perhaps more importantly, would it make sense to go down that road? To me, it sounds like it would be a slightly better way of doing things, but I'm open to other opinions there as well.
You could both load OpenLayers.js library and create map in dialog's open event. That way the page will load faster and you'll skip loading OpenLayers.js if user never opens dialog.
var scriptAlreadyLoaded = false;
$("#dialog" ).bind("dialogopen", function(event, ui) {
if(!scriptAlreadyLoaded){
$.getScript("/scripts/OpenLayers.js", function() {
//Instantiate OpenLayers map when script is loaded
//...
});
}
else{
//It's second time user opens dialog so script is already loaded
//and map instantiated.
}
});
Related
Please see this jsbin test page that illustrates the issue
I have a simple jqm page with two page divs. The only initialization is being done inside a $(document).on('pageshow', function(){}); block. Inside the block, I initialize a fullcalendar.js calendar.
If I load the page as an external page (the first link in the menu) it loads without a hitch (but it's not using ajax, so the page flickers and there's no transition).
If I load the page using the jqm convention of linking to the id of the second page div with an anchor tag, it loads the calendar div as a page with no data.
If I then refresh the page, the data is displayed. Subsequent use of the menu displays both page divs as pages without issue.
I've seen a lot of discussion about which event of the pagecontainer widget to use, and I'm aware that document.ready() is not the way to go. I've tried all the possibilities, I think (pagebeforeshow, pageshow, pageinit, etc.) There's more detail in the demo, where you can see all the code. If I need to post it here, too, I can do that, but it's easier to see the issue if you load the test at jsbin. I suggest running it in a separate window, so you can refresh the page.
If anyone else has solved this or has an idea what I'm doing wrong, I'd really appreciate the help and / or suggestions.
I put all of the pagecontainer events into my test jsbin code and stepped through them. (Thanks to Gajotres for providing useful documentation on the various pagecontainer hooks). It turns out that the one I needed was 'pagecontainerhide' instead of pageshow, pageinit, or any of the others. Once I modified the code to use that event, the calendar displayed properly on the page div, with transition, and I no longer had to click on refresh to see load the "page".
Since I have all the events there, perhaps others with page change issues can benefit from the test page....
I am developing a jQuery Mobile application that will run into a Cordova wrapper.
I am struggling to understand the use of each pagecontainerX event and when to use which.
I will post three specific use cases:
1) hook click events:
Say I want to assign a handler to a certain click event on a button.
2) change textual content of the page:
Say I have a page and I want to update some content that might have changed since last time I have shown the page.
3) change graphical content of the page:
Like if I want to draw on some canvas, or in cases where I need to know how things are rendered and their size.
Preliminary answers:
these is what I have found myself, but I would really much appreciate comments:
1) I am using the pagecreate event, as it's only called once. It is also possible to specify what specific page you want to hook the handler to by doing: $(document).on("pagecreate", "#pageid", handler);
2) I am using pagecontainerbeforetransition or pagecontainerbeforehide. Pagecontainerbeforehide has the advantage that is only fired once, while the other is fired twice (dunno why). Other options, like pagecontainershow, will change the content after transition, which is a bit weird to look at.
3) In this case I am employing pagecontainershow, so that things have already been graphically rendered and I can compute heights and widths etc., the drawback is that the user will see the transition, and only after he will see the content of the page being modified.
Another topic on the much discussed issue of button responsiveness when web apps are used on mobile devices.
I am listening for the touchend event to trigger a radio button being pressed. This solves the issue of making the button more responsive, however creates another problem.
jQuery mobile applies classes such as ui-icon-radio-on, ui-radio-on, ui-btn-hvr-a, ui-btn-dwn-a when the event occurs that get left behind. This makes the button look like it is still being pressed even though the event is over. It ends up being a decent effort to juggle removing and adding all those classes to make everything look right.
My questions is - does anyone have an elegant way of adding and removing the needed classes and attributes.
or
Is there a better way of going about this that will not involve "recreating the wheel" in terms of manually dealing with the styling based on event triggers. Would google's fast button be a better solution? (not sure how to integrate). Is there a simpler way?
$(document).on('pageinit pageshow', 'div:jqmData(role="page"), div:jqmData(role="dialog")', function (event) {
if($(this).hasClass('AdminSurv') && event.type=='pageinit') {
$(this).on( 'touchend', '.ui-radio', function(event) {
event.preventDefault();
/*uncheck all radios in control group to avoid multiple checks*/
var _control_group = $(this).parent();
_control_group.find("input:radio:checked").attr('checked',false);
/*check the radio*/
$(this).find('input').attr('checked', true);
/*much juggling of classes/attributes going on here
still looks like the buttons are being held down
this is a very sloppy example of my initial attempt*/
_control_group.find('label').removeClass('ui-radio-on');
_control_group.find('label').removeAttr('data-icon');
_control_group.find('label span span').removeClass('ui-icon-radio-on');
$(this).find('label').removeClass('ui-radio-off');
$(this).find('label').addClass('ui-radio-on');
$(this).find('label').attr('data-icon','radio-on');
$(this).find('label span span').removeClass('ui-icon-radio-off');
$(this).find('label span span').addClass('ui-icon-radio-on');
});
}
});
Many jQuery Mobile widgets accept refresh method, in which it is used to enhance markup of elements already existing in DOM or are inserted dynamically.
For checkbox and Radio buttons, .checkboxradio('refresh') combined with .prop() are used to enhance/modify the markup by adding/removing classes, for checked and unchecked elements dynamically.
Check
$('.selector').prop('checked', true).checkboxradio('refresh');
Uncheck
$('.selector').prop('checked', false).checkboxradio('refresh');
Demo
Reference: Checkboxradio Widget
In a multi page template,I have three category pages (comedy, action, drama) that you can swipe between each containing rows of images (Seinfeld, Modern Family, Family Guy, Big Bang). Clicking on an individual image should open a dialog box (Seinfeld summary), close when you click the close button, and stay close. Initially it works, then what happens is based on the number images click after two, it opens and closes n -1 (clicking the 3rd image, opens the dialog box twice).
what could be the reason behind this?
Without your code I can be sure but I think I understand what is happening to you.
You have a problem with multiple event binding. Because of jQuery Mobile architecture it is possible to bind an event numerous time to some object.
I have an blog ARTICLE on jQuery Mobile page events handling and there's a chapter dedicated to this problem, just search for the chapter Prevent multiple event triggering. Or it can be found HERE.
In few words always unbind event before you bind it to some object to prevent this from happening:
$('#test-button').die('click').live('click', function(e) {
alert('Button click');
});
There seem to be many questions/answers on how to change Twitter Bootstrap's dropdowns from appearing on a click to appearing on a hover. The builders of Bootstrap have a good reason for using click instead of hover -- hover doesn't work on most tablets & phones. However, one of the reasons why I am using Bootstrap is for its responsive features. I want one site that can be viewed on desktops, tablets and phones. Although clicking to get the dropdown is necessary for tablets and phones, it is not the expected behavior for desktops. I'd like my site to be responsive, but not at the expense of having to retrain the users!
Is there a way to serve up hover dropdowns for desktops and click dropdowns for tablets and phones?
I created a plugin (working on a couple refinements, but it definitely works as is) that allows dropdowns to work on hover, but it doesn't interfere with Twitter Bootstrap's click event, so you can safely bind both, which essentially means if there is a mouse, it will activate on hover, but if there's not a mouse (i.e. a touchscreen on a tablet), it will still activate when clicked.
I have the plugin hosted on GitHub: https://github.com/CWSpear/twitter-bootstrap-hover-dropdown
It works by explicitly calling it, but I'm going to tweak the code to work with data-attributes in the near future.
You can with "Responsive utility classes"
http://twitter.github.com/bootstrap/scaffolding.html at the bottom of the page
I was searching exactly for this. And I've found better solution ( I think ).
We can easily do this using awesome Modernizr.js library.
We can detect the touch screen device by the below function.
function is_touch_device() {
return !!('ontouchstart' in window);
}
And then we can disable the URL in the hyperlinks dynamically via Javascript either by changing the location to "#" or by preventing the default action of the parent menu items.
Final code would be as below.
$(document).ready(function() {
/* If mobile browser, prevent click on parent nav item from redirecting to URL */
if(is_touch_device()) {
$('#mainmenu li > ul').each(function (index, ev) {
/* Option 1: Use this to modify the href on the <a> to # */
$(ev).prev('a').attr('href' ,'#');
/* OR Option 2: Use this to keep the href on the <a> intact but prevent the default action */
$(ev).prev('a').click(function(event) {
event.preventDefault();
});
});
}
});
For more details, you can see this link
I do believe someone will vote me UP :-)
Thanks