Twitch has introduced a functionality that, when you've opened a stream page and navigate to a different part of the site, allows the video to keep playing in the bottom left corner without any interruption. This even works when pressing the back button in the browser and only breaks when closing the tab or manually typing in the URL you want to go to (e.g. https://www.twitch.tv/directory/discover).
I've been trying to figure out how this is being done. The video is embedded into a div with the class "js-player-persistent", so I assume it has something to do with a JavaScript and getting data from the session storage, but I'm unsure how much effort this requires specifically.
Twitch is built on EmberJS on the front end making it a Single Page Application (SPA). This allows them to not have to reload the page as you navigate, they simply utilize AJAX to load in the data needed to show the next page in a prescribed window. This is accomplished by the browser's pushState API or the hashbang implementation for browsers that don't utilize pushState.
Looking at their implementation of it, they likely have a hook that looks for navigation changes, before it happens, off the video player and at that time create a DOM element in that corner and put the video in it, then they proceed with changing the main page to wherever you are going.
This is fairly easily done in most SPA front ends like Angular, React, Ember, Vue, etc. and is a major bonus to them.
Twitch is an Ember app, which means it is a Single Page Application. It does not reload the whole page when you navigates between "pages". Regarding the use of the browser's navigation buttons, JavaScript routers take advantage of the browser history API to simulate a normal navigation.
After my original comment got as much popularity as it did, I figured I'd explain my presumption a bit better.
Twitch is a SPA, or Single Page Application. This means that when you go to a new "page" on the Twitch website you aren't actually going to a new webpage, you are loading a new view. Each of these views are basically sections of content that seem like pages but don't reload the entire page. This is commonly used with cross platform mobile apps.
The pros of Twitch doing this is that they communicate with their back-end constantly and the site handles that well with the streams. (They recently switched from a Flash to HTML5 video player.) This as well as having your current stream constantly playing even though you are exploring different sections of the website is a major plus for them.
The cons of all this is that your browser has to do more rendering meaning it is more intensive for your computer. And it is worth mentioning SEO can be harder with SPAs.
Related
Do any of you know how can I share a component between several html pages but load it only once?
I`m trying to share a unit canvas between several pages, but it takes too long to load, so every time I change the page it loads again, causing a very poor user experience. I tried to create the frame once and put it on session to be reused, but it seem to be not the fix for it.
I need to use the same component amongst all the pages without reloading it every time the user changes the browser address.
Thank you.
we had the same problem with adding the communicator to out online app (something like on FB). The best solution is to do a single page application and manage urls by html5 history API, but is only applicable when you start development. You could also try something with iframe e.g. put canvas in main document and the rest (changing part) in iframe, but you will have a problem with urls, so it isn't solution.
Becouse we had working app when we started work on communicator we ended up with everything store in session like you did.
I've been learning about angularjs and have been very confused about how angular manages to change pages without refreshing and yet have a completely different view.
Are they actually changing the page URL or just hiding all the elements of on page and showing the other?
This video by CodeSchool explains it quite well.
AngularJS is just a tool that allows you to build single-page web applications with relative ease. What you are looking for is actually the definition of Single-Page Application:
Single-Page Applications (SPAs) are Web apps that load a single HTML page and dynamically update that page as the user interacts with the app. SPAs use AJAX and HTML5 to create fluid and responsive Web apps, without constant page reloads. However, this means much of the work happens on the client side, in JavaScript.
Also, from http://www.johnpapa.net/:
A SPA is fully (or close) loaded on the initial page load, it’s key
resources are preloaded, and progressively downloads features as
required.
And, more specific to your particular question:
When a user clicks on a menu item, the SPA sees that url and
translates it to a View that should be displayed. If the view has not
been seen before, the application may make an HTTP request to retrieve
the HTML template for the view. Then it will compose the view, fill in
the template, and display the view in the appropriate location within
the shell. If the view has already been viewed once, the browser may
have cached it and the router will be smart enough not to make the
request. This is one way a SPA can reduce round-tripping to and from a
server, and thus improve performance.
Keep in mind that this behavior is attained with the use of JavaScript, and does NOT require any specific library or framework (such as AngularJS), although you will probably want to learn how to use one to facilitate the process.
I also recommend you check these resources:
http://johnpapa.net/building-single-page-apps-with-knockout-jquery-and-web-api-ndash-the-story-begins/
http://www.johnpapa.net/pageinspa/
If your url's are mapped with the $routeProvider, you can reload a controller invoking $route.reload().
How is it possible that web applications like Google Maps and Mixcloud update their urls without the use of a hashbang (also known as #!)?
Notice for example the coordinates right after the # sign in the URL while swiping the view in Google Maps. Or note that the music keeps playing while following some links.
I'm looking for a programmatic way to achieve the same functionality and I would also like to know how this works.
The HTML5 history API is a standardized way to manipulate the browser history via script. Part of this API — navigating the history — has been available in previous versions of HTML. The new parts in HTML5 include a way to add entries to the browser history, to visibly change the URL in the browser location bar (without triggering a page refresh), and an event that fires when those entries are removed from the stack by the user pressing the browser’s back button. This means that the URL in the browser location bar can continue to do its job as a unique identifier for the current resource, even in script-heavy applications that don’t ever perform a full page refresh.
Source: http://diveintohtml5.info/history.html
Have you taken a look at ASP.Net MVC? It uses the single page application concept. I'm not entirely sure what you're looking for but this is a good example: http://www.microsoftvirtualacademy.com/training-courses/introduction-to-asp-net-mvc
You also might want to look at AngularJs, which makes routing urls really easy.
I wonder how sites like SoundCloud work: you play a song and it keeps playing even if you move to another page without stopping
Any suggestions?
The only way I can think of is to build your app, or at least the parts of it that need to bo continuous, as a single page.
In practice, this means that only one HTML document is loaded. When, say, a link is pressed, the browser action is intercepted and prevented and the browser behaviour is faked by javascript.
Consider a website consisting of pages A and B. Normally, when a link pointing to B is activated, the URL is changed and the browser calls the server, requesting B. In a single-page application, however, this is interrupted by a javascript function, which changes the URL using the History API, and then displays B in a way that doesn't require a new document being synchronously fetched from the server.
There's a couple of ways to do it.
Navigate to a new page
If you do that, a whole new JS execution context is created for the new page, so you can't keep the function running. What you can do however is to "resume" execution in the new page. For this you need to save the state of the old page either on the server or in some client storage that persists between page changes (cookies, localStorage, etc).
Fake navigation
This is the most user friendly way - you turn your website into a web application. You no longer have multiple pages, so when user wants to change what he sees in the browser (like go to a new song), the app simply changes the appropriate area with the desired content. This is a complex topic that should probably be researched in itself, not explained in a SO answer. Go ahead and google "single page application" and you should find plenty of resources for it.
Technically you never change the page when you are using souncloud. You always stay on the same page and only the parts get changed which are actually changing, so you never reload the whole page. That's why they can keep the music playing: They just never remove or change the actual player. If you are wondering why the URL in your browser is changing if you never leave the page: They manipulate your history entries.
If you are interested in creating an application that behaves similar you should checkout frameworks like Ember.js or Angular.js. TodoMVC Gives a nice overview of those frameworks.
I'm using an ASP.NET server side control for playing mp3, of course I can use javascript or flash controls for doing so, but my problem is that I want the music to be played only once (at site start up), and its playing should continue when user displays new pages, I've used this control in master page, I don't want the music to be restarted whenever a new page is loaded, how can I solve this problem?
thanks
Frames should generally be avoided, especially when it comes to layout. However, I think this is one case where a frame might be suitable since it ensures that the rest of your page can be refreshed without refreshing the frame page. The same can be achieved with AJAX, but I don't know how your site is structured and if it would require a huge rewrite to implement AJAX. So, you could create a small frame and have the music play from there. More information on frames and ASP.NET can be found here.