I have a profile image upload page, where users can overwrite their previous profile picture.
But when I return the users to their profile page the browser has cached their previous image and only an F5 refresh returns the new image.
Is it possible to prevent the browser from caching the image, as some users might think their new upload failed.
Ideally I would want to only prevent the image from being cached. But a quick look at donut-caching seems to suggest its not possible to do in MVC2...??
Thanks for any pointers.
Preventing caching is a very bad idea. Rather, consider using technique with explicit "version":
http://www.example.com/users/johndoe/avatar.jpg?43567
Just increment this number every time an avatar is saved and you're good to go. Or, instead of having an explicit version, you can use value of UpdatedOn date/time column (if you have one) converted to ToFileTime().
Related
Okay I do not know how to explain this to you, It may be just my internet, or maybe my site is slower, or they really have a technique for doing this.
If you visit Facebook, Reddit, Youtube, Twitter, and if you click on links or any actions on those websites, the url changes but the browser tab doesn't show any loading circle.
How do they do that?
I am pretty sure my website is fast enought and at times it loads even faster than the bigger sites, but mine shows the loading circle on the browser tab.
Okay so I found the answer. Here is the technique for changing the url without reloading the page.
Updating address bar with new URL without hash or reloading the page
How do I modify the URL without reloading the page?
I am still trying to figure out though how to redirect the actual page without reloading the entire page. I am guessing they are loading it via ajax or something similar upon url change. I'll update this once I figure it out.
Edit: I am currently working on this feature for my site. The technique is to use ajax to load the content based on the url. I'll update this thread more as I update my site with this feature.
Edit 2: Damn, you will probably face the same problem I had trying to detect the url change without using onhashchange. If so, here you go:
How to detect URL change in JavaScript
This literally took me 4 hours just to figure that one out.....
Edit 3: I have now integrated this feature on my site. You can check it at
Grandweb
It is quite simple, but lots of work in appending the content once retrieved via ajax. So here is the process:
I am using pushState(); to change the url without reloading the page.
var url = $(this).attr('href');
var split_url = url.split('/');
var new_url = url.replace('https://grandweb.net/','');
window.history.pushState("object or string", "Title", "/write");
Using 'mouseup' was a bad idea, I changed my mind.
I then have to trigger the first function using 'mouseup' to retreieve the content via ajax, and then listen to succeeding onpopstate() for the next ones, because some mouse actions such as Mouse 4 or Mouse 5 are bound to the browser's Back and Forward button, and does not trigger via 'mouseup'.
$(window).on('mouseup', function(evt) {
get_content();
}
window.onpopstate = function(event) {
get_content();
}
The first one is responsible for triggering the function on first try because onpopstate only listens only when the browser's history API is populated.
Using mouseup was a bad idea, basically, don't use it unless you really want to detect mouse action from anywhere on the document.
I instead use the anchor tags/links to trigger the first function for retrieveng content.
example:
<a class="dynamic_btn" href="website.com/post">Home</a>
then
$(document).on('click','.dynamic_btn',function(e){
e.preventDefault();
get_content();
});
Using onhashchange is possible IF you have hashes on your url. I do not use hashes on my url so basically onhashchange is useless in my use case, unless I do not know something.
After retrieving the contents, I append them via creating DOM elements to existing containers from the page.
This is much easier to do if you are planning to change few elements or containers in your pages. If you plan on doing this to change a full page layout, goodluck. It's doable, but it's a really pain in tha *ss.
Upon observing Facebook, I learned that they do not implement this technique in all of their links/features. It makes sense because this is harder to maintain most especially because most of the work here is being done client side. It is very nice though because the page doesn't load.
I have implemented it on a few 'essential' functions of my website such as the viewing of posts and returning to the homepage. I can implement it on the whole site, but I am still deciding on that. That is all, thank you very much for reading internet stranger.
I'll admit that I'm pretty new web development (only been coding for about a year) and especially green when it comes to JS / jQuery.
A specific web page I've built loads different data based on hovering over certain categories: country clubs, resorts, hotels, etc. When I built the site on my local machine, the javascript function was super quick. However, on the live site, it has a long delay before the data swap happens.
The URL is: http://preferredparkingsolutions.com/client_list.html
Which links to a javascript function at: http://preferredparkingsolutions.com/scripts/clientHover.js
Which replaces the display div (#client_list) by pulling data from a text file.
Is there a better / faster way of doing this?
Yes, this could be optimised by loading the content in up-front and caching it. Currently you are doing a HTTP request each for each and every hover - even if the user has hovered over that element before, since the AJAX responses aren't being cached. Doing this would be your quickest win.
However, I can't see any case at all for having the content live externally. Is there any reason you're against having the content physically in the page and just using show/hide methods? There's various benefits to this - SEO, for one thing, since Google will find the content.
this is the external page you are loading http://preferredparkingsolutions.com/client_list.inc.html and the content looks little and looks like its a static page then why not just load every thing upfront and then just hide and show div's ? as Utkanos suggested you will aslo have a SEO benifit and also its HTTP request each for each and every hover. if you still want to load it externally lost load it once and cache it and use the cached version to hide and show divs.
I want to design a web album with every image in the album having it's own title, and description. So, at a time only one set of image, title and description would be visible. And on clicking next button, the next set of image, title and description would appear,and so on.
So am wondering, what would be the best way to design with? HTML or AJAX?
I don't want to use the ready to use tools such as lightbox.
Do you want the browser's back button to work? If so, then you should make your life simple
and use html (since you will only be displaying one image at a time either way).
Ajax implies using html. On the other hand, using html does not necessarily imply that you need to use AJAX to load content dynamically.
What is the purpose of this project? If you are doing it for the learning experience you should go on with AJAX (from scratch). If you want speed and quality use an existing web image gallery. If you need to write it yourself use plain html (or an ajax framework such as dojo, jquery, etc. this will save you a lot of pain solving cross-browser quirks).
In addition, if you want to be able to click a button to take you to the next (previous) image
and you don't know how many images you will have beforehand, then you are looking for dynamic behavior. You can code dynamic logic either on the client side (javascript), or on the server side (let's say "php" to start with).
Also, how do you plan to keep the corresponding (image, title, description) together?
If you only have a 3 images, say you could hard code each of this into its corresponding html file. eg. 1.html, 2.html, 3.html. Then you would have to point the forward button from a.html to point to b.html. etc...
If you didn't want this boring static behavior and wanted something smarter, say you decided for AJAX. Then you would only have 1.html file and from there (using javascript) you would ask your server for the (image, title, description) and load all that (dynamically, without refreshing the browser) into the same page. The easiest way to get this from the sever is by just reading a a static (XML, or JSON) file which contains all the info (image urls, titles, descriptions). Then with javascript and using DOM manipulation you would remove the old image, and add the new one.
However, this would all be a lot simpler with server-side processing (and it's worth learning). In this case you could have a url which takes a parameter with the image number. eg. http://example.com/gallery/index.php?image=X
then before the server responds to the client with the html, it would realize that you want to load image X so it would get it's corresponding description, title, and url. and "embed" those into the file. Of course, depending on the number, it would also add the right links for the previous and next buttons. Eg. If the currently displaying image was 9 then forward button would "dynamically" be determined to link to (X+1) : http://example.com/gallery/index.php?image=10
The newer versions of Firefox have a new 'feature' that remembers the stuff that was filled out in a form and repopulates the form with these values on refresh (maybe in other situations as well?).
The problem is we have a quite complicated web application which uses a fair bit of ajax and hidden form fields which are never filled out by the user, but by javascript.
Because of this new 'Feature' we get a lot of errors when refreshing form because these fields are suddenly populated with invalid values.
So i'm looking for a way to turn this 'feature' off without disabling auto-completion. (because that IS useful on the fields our customers fill in)
if i put
autocomplete='off'
in my html, the effect is disabled, but this loses auto-completion (obviously).
the problem is in fields getting filled in after a refresh without any user action.
While the password manager will populate a username and password if there is exactly one match, autocomplete itself doesn't automatically populate fields. But I'm guessing you're thinking about the sort of refresh you get, say, if you reload the page. In this case the field values are restored by session history, but you might be able to turn that off by marking your page as uncacheable.
Well you should set the value of these fields to nothing or or whatever default value they have using javascript right before you start your other javascript/ajax tasks.
It is a browser feature - without going into the settings of each client browser you can't disable this.
I suggest more robust validation - client and server side.
After the page is loaded, but before you do any other logic, you should force the value to be empty:
inputElem.value = '';
Here is a jQuery solution I put together.
It doesn't disable the autofill, rather it overrides the fields after the browser has done it's thing.
I was trying to fight Chromes autofill when I made this. Just using .val('') on it's own didn't work since it triggered before chromes autofill functionality kicked it.
var noFiller = $('input[type="text"]');
noFiller.val(' ');
var t=setTimeout(function(){
noFiller.val('');
},60);//keep increasing this number until it works
The Javascript solution (setting field values to empty when the page loads or updates via Ajax) has already been mentioned.
Another option might be to generate the ids of your fields with random numbers attached to them so that the browser can't match them to cached values, but this may screw up other things.
Autocomplete isn't a new thing. Every browser has it. See this http://www.w3.org/Submission/web-forms2/#the-autocomplete
Autofill? Are you sure? Check your input's value attribute with Firebug (Firefox addon). Check you post and response in your ajax. Maybe your ajax is filling it behind scenes.
BTW: remenber to disable any external toolbar. There are some toolbars for Firefox/IE/Chrome/etc that autofill data for the user. Warning with this.
I know this question might sound a little bit crazy, but I tough that maybe someone could come up with a smart idea:
Imagine you have 1000 thumbnail images on a single HTML page.
The image size is about 5-10 kb.
Is there a way to load all images in a single request? Somehow zip all images into a single file…
Or do you have any other suggestions in the subject?
Other options I already know of:
CSS sprites
Lazy load
Set Expire headers
Downloads images across different hostnames
There are only two other options I can think of given your situation:
Use the "data:" protocol and echo a base64 encoded version of your thumbnails directly into the HTML page. I would not recommend this since you cannot then cache those images on the users browser.
Use HTML5's Web Storage to store all the images as records with the base64 encoded image data stored as BLOBs in a column. Once the database has downloaded to the users machine, use Javascript to loop through all the records and create the thumbnails on the page dynamically using something like jQuery. With this option you would need to wait till the entire database was done downloading on the end users browser, and they will need a fairly modern browser.
I think your best bet is a combination of lazy loading, caching with expires headers and serving images from multiple hostnames.
If the images can be grouped logically, CSS sprites may also work for you in addition to everything above. For example, if your thumbnails are for images uploaded on a certain day...you may be able to create a single file for each day which could then be cached on the users browser.
This is done by using what's called a CSS sprite; a single image with all the other images inside it, with the particular part that's wanted in the html selected by css.
See one tutorial at http://css-tricks.com/css-sprites
It sounds like you want something like SPDY's server push. When the client requests the HTML page (or the first image), SPDY allows the server to push the other resources without waiting for more requests.
Of course, this is still experimental.
You could try the montage command of imagemagick to create a single image.