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  • Hello, and welcome to another episode of GDL-IL, GDL Israel.

  • Today we're going to keep it really condensed and speak

  • about a few HTML5 APIs, or features, that you could

  • leverage and use today.

  • Some of them, I find, are really simple to implement,

  • and could save you lots of unnecessary work.

  • And I think the line that just connects all of them is that

  • they got some nice adoption today now

  • in different browsers.

  • And you could definitely leverage them and use them.

  • And those APIs, or in a way, the browser features, will

  • enable you to save code, which is always great, because less

  • code, less time you need to spend reading it, maintaining

  • it, et cetera.

  • And in some of them, it's just a better way, or more

  • efficient way to do things.

  • So let me just share my screen with you.

  • And actually, the demo that I've prepared is live.

  • So you are more than welcome to go to my site and just play

  • with the page itself.

  • All the code is on the page, and all the code snippets are

  • gists, so you could check them on GitHub or on my page.

  • Let me share my string.

  • And yeah, hopefully you could see it quite clearly.

  • [INAUDIBLE]

  • DevTool as well.

  • Just so you could see.

  • And maybe we'll throw the DevTool just to the bottom,

  • because we don't need the real estate of the page itself.

  • I'll make everything much bigger.

  • So hopefully [INAUDIBLE]

  • code easily.

  • And basically, as you can see now, we have a

  • few examples here.

  • And we could probably start with the most basic one, the

  • Geolocation.

  • So the Geolocation API is with us for a long time.

  • And if you want to see on which browsers this nice

  • feature will be supported, you could check it on the search

  • box that I prepared.

  • And if you'll type here, Geo, and click, you'll be

  • redirected to a site that we mentioned a few times in the

  • past, which is called caniuse.com.

  • And on Geolocation, for instance here, you can see

  • quite clearly that the current version of browsers, basically

  • supported on all the browsers.

  • So IE, Firefox, Chrome, Safari, and

  • Opera on the desktop.

  • And on the mobile arena, we have from iOS to Android.

  • Quite a nice support.

  • So it's definitely a feature that you could use.

  • Here I just choose to show you a few interesting things.

  • So as you can see here, we're using the

  • navigator.geolocation to do the feature detection.

  • So in case our browser, for some reason, the user

  • browsers, is not supporting this feature, it's quite

  • clearly that we could communicate it nicely.

  • And since here we are all developers, I'm just using the

  • console.log.

  • But you could do something much better when you are

  • running your own code, and communicate this information

  • to the user.

  • However, when we do have this feature, we're just going and

  • calling the navigator.geoloc ation.getCurrentPosition, and

  • transferring it a callback function with the position.

  • So we could gather the latitude, longitude, of the

  • position, and then do some interesting stuff.

  • Now what I wanted to show you that I'm doing here, and as

  • you can see here, I'm basically extracting the

  • address from the GeoPoint.

  • And that's actually, I think, less than five lines of code

  • in JavaScript.

  • So let's just go here and see how we look like.

  • And if we'll open the source--

  • and I just put all the source code of this

  • page in our main page--

  • let's do it here.

  • And see here.

  • Let's not check that iframe that I embedded from GitHub.

  • Let's just see the code itself of our page.

  • In here in our page itself, I could in DevTool click

  • Command-F, search for Geo, and check.

  • And in our case, it will be in this div.

  • And what we are basically doing here is just going and,

  • in this script, we are calling basically Google Maps API.

  • Now you can see here--

  • I'll make the code [INAUDIBLE]

  • easier.

  • What I'm doing here is just going to the Geolocation.

  • And once I have the point itself, I'm just going to

  • Google Maps API, and transfer to it, just here, the

  • longitude, latitude, and the GeoPoint that I built from

  • those two parameters, and with sensor false.

  • It could be sensor true.

  • And then the user will need to confirm that they agree to

  • share their location.

  • By the way, you can see here a nice indication that you see

  • this page is tracking your location.

  • So the user needs to approve it for the first time.

  • And once we are doing that--

  • let's get back to our code--

  • just over here in the script, we are--

  • oops.

  • Yeah.

  • We are going here, and going and getJson.

  • So we'll get an array of results from Google Maps API.

  • And in our little case, I'm running on each and every

  • result here.

  • And as you can see here, I'm printing the different results

  • to the console.

  • And for our little example, I'll just choose the first

  • result, which usually will be with the highest quality.

  • And I'm just outputting to the screen right here.

  • So Geolocation is one neat API that you could leverage today.

  • Another very cool one is the Summary Object.

  • So today, without any JavaScript, you could play and

  • get this summary detail aspect of things without any line of

  • JavaScript.

  • And if we'll go here and do Inspect Element, basically you

  • could see that you could tell the browser that you have here

  • an element.

  • It's not a div.

  • It's Detail and Element, and a Summary, which basically is

  • giving you the header or the main title of this element.

  • And then you could expand and collapse it just

  • by clicking on it.

  • So it's very nice.

  • Here, as you can see, I just put a paragraph in it to

  • explain it.

  • But really sweet and short ability to work with HTML

  • Markup, and tell the browser exactly what we want.

  • And in this case is, of course, an expandable div that

  • shouldn't be just a div with the JavaScript running on it,

  • but rather just to communicate and using the right elements.

  • In this case, it's Detail and Summary.

  • Local Storage is another one, a very simple API that I

  • highly encourage you to check.

  • The code snippet here is so simple, so you could

  • understand that it's really the most basic one.

  • And one important thing to note about this API that it is

  • synchronous and not asynchronous.

  • So it's better to use few keys with large

  • payload in the value.

  • And then it would be more efficient.

  • Or if you have the need to do it asynchronously, and use

  • lots of data, probably check out IndexedDB, which will work

  • much better, and give you a full blown database, and not

  • just a key value API like Local Storage.

  • Now, with Local Storage, you're just

  • calling it with setItem.

  • And you have immediately the key value.

  • And to retrieve, you just need to go to Local Storage with

  • the right key, and you'll retrieve the answer.

  • One nice thing here that I prepared is just-- you could

  • see that I wrote it in Hebrew-- but you could, for

  • the example, say something like, "hey" and "bye." Store

  • it, and after we do that, if we go with the key of--

  • here it's meaning in Hebrew, shalom--

  • it will retrieve--

  • we don't have anything.

  • But if we go here and do "hey," and retrieve, you can

  • see that I have "bye," because that's what I put in here.

  • One nice thing to debug and see what we're doing with

  • Local Storage will be to go to the Resources tab.

  • And here in the Resource tab, you can see here that in Local

  • Storage, I basically have a nice view of the

  • keys and the value.

  • And if I put here some more.

  • Let's do "hey all." And let's save it.

  • So you see here that I have now another element.

  • And very simple, and easy to work with this nice API,

  • especially if you want to debug it through leveraging

  • Chrome DevTools.

  • Another nice option is WebRTC.

  • Now I'm sure some of you noticed that the browser is

  • notifying me here that this specific domain, which I'm

  • holding all my projects, ido-green.appspot.com, I want

  • to use my camera.

  • Now in this case, of course, I will allow it, because I know

  • who and why we want to do it.

  • And if we go to the WebRTC example, and we close the

  • DevTool for a second, one, you could see that the page

  • containing moi.

  • And the other nice point is that the code to do so is

  • very, very simple and trivial.

  • First, we're just getting hold of our getUserMedia.

  • And for the ones that doesn't know, if we search here quite

  • quickly, WebRTC, you could see that we're supporting--

  • let's do Web [INAUDIBLE].

  • So getUserMedia, which is the right way to call it, will be

  • supported in the near future on IE 11.

  • And it's currently supported in Firefox, Chrome, and Opera.

  • So when we're going to our code, you can see that I'm

  • calling getUserMedia.

  • Hopefully, it will be the standard, and all the browsers

  • will support it.

  • And for now, I'm just checking and making sure that I get a

  • hold through that prefixes for WebKit and Moz for Firefox.

  • Once I do that, I have here my callback.

  • And this callback is basically being set it here.

  • And the errorCallback to just make sure that we are

  • communicating right now to ourselves what's happening in

  • case that things are not going smoothly, and a few

  • constraints.

  • So in our case, we'll just do the video capturing, but you

  • could do it with audio, as well.

  • Now, when we successCallback, and basically have the

  • localMediaStream that I'm just attaching to a [INAUDIBLE].

  • And then in my case, I have a video tag that now I'm

  • getting hold on.

  • And this video tag, I'm basically taking the video

  • source-- and that's one of the beauty in this API, that

  • basically we're leveraging the same good, old attributes that

  • we had in the video element.

  • And here in video.src, I could just attach to it instead of

  • just an empty for file.

  • And just attaching this localMediaStream.

  • And by doing so, I'm just creating a URL.object that

  • will be able to stream it to the video element.

  • And when I'm clicking Play, basically, the result here is

  • that you could see and work with this

  • stream for your usage.

  • Visibility API is actually a very nice API that gives you

  • the ability to see what the users are actually exposing to

  • in your current tab or window.

  • So when the user is flipping--

  • and you can see here that they flipped several times from

  • caniuse and back to our page--

  • each time I did so, a new event was triggered.

  • And right now I just put it on the page itself, so you could

  • all see it.

  • But you can imagine that you could stop the video playing,

  • for instance, or do other clever things when the users

  • are not really paying attention or focusing on the

  • current tab or window that you are doing.

  • In order to get this, we're just attaching the listener to

  • the visibilityChange.

  • And then we could do whatever we like.

  • Our support here, a nice tutorial that my colleague

  • John [INAUDIBLE] wrote, giving you a very nice capability of

  • how to use this nice API.

  • Device Orientation, of course, as you all know, on mobile

  • devices, we have the ability to work with the

  • accelerometer, and get what the device itself is doing now

  • in a 3D environment.

  • And we've got those three params on the alpha, beta and

  • gamma axles.

  • And basically, this API is really nice if you are

  • developing any web app that will want to use or leverage

  • the capabilities of the mobile browsers, or on the

  • tablet, or on phones.

  • I think we covered most of the things that I wanted here.

  • And as I promised, today we'll keep it real short.

  • And if there's any question on HTML5 APIs, please feel free

  • to reach out to me on plus.google.com-+idogreen, or

  • on Twitter @greenido, is one word.

  • And if some of the viewers got some questions right now,

  • please feel free to ask.

  • Let's see if we have some questions on the chat.

  • No, we don't.

  • So until next time, be strong and safe, and see you.

  • Bye.

Hello, and welcome to another episode of GDL-IL, GDL Israel.

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A2 初級

你今天可以使用的HTML5 API (GDL-IL) (HTML5 APIs You Can Use Today (GDL-IL))

  • 65 5
    altas 發佈於 2021 年 01 月 14 日
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