1 00:00:00,188 --> 00:00:04,190 Let's start a section with a general overview 2 00:00:04,190 --> 00:00:06,750 of Modern JavaScript Development. 3 00:00:06,750 --> 00:00:10,760 So basically of how we write JavaScript today. 4 00:00:10,760 --> 00:00:13,230 Because when we built applications, 5 00:00:13,230 --> 00:00:17,350 we don't just write all of our code into one big script 6 00:00:17,350 --> 00:00:20,780 send that script as it is to the browser, 7 00:00:20,780 --> 00:00:22,590 and call it a day. 8 00:00:22,590 --> 00:00:24,640 Now it used to be like this, 9 00:00:24,640 --> 00:00:27,360 but the way we built JavaScript applications, 10 00:00:27,360 --> 00:00:31,373 has changed tremendously over the last couple of years. 11 00:00:32,940 --> 00:00:34,650 So back in the day, 12 00:00:34,650 --> 00:00:36,480 we used to write all our codes 13 00:00:36,480 --> 00:00:40,720 into one big script or maybe multiple scripts. 14 00:00:40,720 --> 00:00:45,190 But today, we divide our projects into multiple modules 15 00:00:45,190 --> 00:00:48,210 and these modules can share data between them 16 00:00:48,210 --> 00:00:52,240 and make our code more organized and maintainable. 17 00:00:52,240 --> 00:00:54,930 Now, one great thing about modules 18 00:00:54,930 --> 00:00:58,160 is that we can also include 3rd-party modules 19 00:00:58,160 --> 00:01:00,100 into our own code. 20 00:01:00,100 --> 00:01:03,500 And there are thousands of open source modules, 21 00:01:03,500 --> 00:01:05,630 which we also call packages, 22 00:01:05,630 --> 00:01:09,590 that developers share on the NPM repository. 23 00:01:09,590 --> 00:01:14,120 And we can then use these packages for free in our own code. 24 00:01:14,120 --> 00:01:18,520 For example, the popular React framework or jQuery, 25 00:01:18,520 --> 00:01:20,840 or even the Leaflet library, 26 00:01:20,840 --> 00:01:24,210 that we used before in our Mapty project. 27 00:01:24,210 --> 00:01:27,523 All of these packages are available through NPM. 28 00:01:28,380 --> 00:01:31,920 Now NPM stands for Node Package Manager, 29 00:01:31,920 --> 00:01:35,030 because it was originally developed together 30 00:01:35,030 --> 00:01:38,650 with Node.js and 4Node.js. 31 00:01:38,650 --> 00:01:41,550 However, NPM has established itself 32 00:01:41,550 --> 00:01:43,560 as the go to repository 33 00:01:43,560 --> 00:01:45,520 for all kinds of packages 34 00:01:45,520 --> 00:01:48,210 in Modern JavaScript Development. 35 00:01:48,210 --> 00:01:50,810 Now, in order to actually download 36 00:01:50,810 --> 00:01:53,660 and use and share packages, 37 00:01:53,660 --> 00:01:58,050 we use the NPM software installed on our computer. 38 00:01:58,050 --> 00:02:01,220 And this is just a simple command line interface 39 00:02:01,220 --> 00:02:03,970 that allows us to do all that. 40 00:02:03,970 --> 00:02:07,570 So basically NPM is both the repository 41 00:02:07,570 --> 00:02:10,910 in which packages live and a program that we use 42 00:02:10,910 --> 00:02:15,910 on our computers to install and manage these packages. 43 00:02:16,010 --> 00:02:20,470 So let's say that we are done writing our project code. 44 00:02:20,470 --> 00:02:23,340 So we divided it into multiple modules 45 00:02:23,340 --> 00:02:26,900 and we included some 3rd-party modules as well. 46 00:02:26,900 --> 00:02:30,650 And so now the development step is complete. 47 00:02:30,650 --> 00:02:34,790 However, usually that's not the end of the story. 48 00:02:34,790 --> 00:02:38,890 At least not when rebuilding a real world application. 49 00:02:38,890 --> 00:02:41,120 Instead, our project now needs 50 00:02:41,120 --> 00:02:43,260 to go through a build process, 51 00:02:43,260 --> 00:02:47,590 where one big final JavaScript bundle is built. 52 00:02:47,590 --> 00:02:49,420 And that's the final file, 53 00:02:49,420 --> 00:02:53,190 which we will deploy to our web server for production. 54 00:02:53,190 --> 00:02:55,970 So basically it's the JavaScript file, 55 00:02:55,970 --> 00:02:59,610 that will be sent to browsers in production. 56 00:02:59,610 --> 00:03:02,350 And production simply means that the application 57 00:03:02,350 --> 00:03:06,740 is being used by real users in the real world. 58 00:03:06,740 --> 00:03:10,520 Now, a build process can be something really complex, 59 00:03:10,520 --> 00:03:12,390 but we gonna keep it simple here 60 00:03:12,390 --> 00:03:14,830 and only include two steps. 61 00:03:14,830 --> 00:03:17,680 And the first step, we'll bundle all our modules 62 00:03:17,680 --> 00:03:20,390 together into one big file. 63 00:03:20,390 --> 00:03:22,660 This is a pretty complex process 64 00:03:22,660 --> 00:03:25,210 which can eliminate unused code 65 00:03:25,210 --> 00:03:27,453 and compress or code as well. 66 00:03:28,350 --> 00:03:32,790 Now this step is super important for two big reasons. 67 00:03:32,790 --> 00:03:36,750 First, older browsers don't support modules at all. 68 00:03:36,750 --> 00:03:40,300 And so code that's in a module could not be executed 69 00:03:40,300 --> 00:03:42,560 by any older browser. 70 00:03:42,560 --> 00:03:45,720 And second, it's also better for performance 71 00:03:45,720 --> 00:03:48,160 to send less files to the browser, 72 00:03:48,160 --> 00:03:49,950 and it's also beneficial that 73 00:03:49,950 --> 00:03:53,140 the bundling step compresses our code. 74 00:03:53,140 --> 00:03:55,460 But anyway, as the second step, 75 00:03:55,460 --> 00:03:59,100 we do something called transpiling and polyfilling, 76 00:03:59,100 --> 00:04:00,940 which is basically to convert 77 00:04:00,940 --> 00:04:02,890 all modern JavaScript syntax 78 00:04:02,890 --> 00:04:06,560 and features back to old ES5 syntax, 79 00:04:06,560 --> 00:04:09,200 so that even older browsers can understand 80 00:04:09,200 --> 00:04:11,470 our code without breaking. 81 00:04:11,470 --> 00:04:16,080 And this is usually done using a tool called Babel. 82 00:04:16,080 --> 00:04:18,910 So, remember that I said right in the beginning 83 00:04:18,910 --> 00:04:21,620 of the course, that we were gonna do this, 84 00:04:21,620 --> 00:04:25,090 and in this section, we will finally do it. 85 00:04:25,090 --> 00:04:29,090 So these are the two steps of our build process, 86 00:04:29,090 --> 00:04:31,030 and after these two steps, 87 00:04:31,030 --> 00:04:33,940 we end up with that final JavaScript bundle, 88 00:04:33,940 --> 00:04:37,920 ready to be deployed on a server for production. 89 00:04:37,920 --> 00:04:41,920 Now, of course we don't perform these steps ourselves. 90 00:04:41,920 --> 00:04:45,070 Instead, we use a special tool to implement 91 00:04:45,070 --> 00:04:47,080 this build process for us. 92 00:04:47,080 --> 00:04:49,600 And the most common build tools available, 93 00:04:49,600 --> 00:04:52,910 are probably webpack and Parcel. 94 00:04:52,910 --> 00:04:55,590 And these are called JavaScript bundlers 95 00:04:55,590 --> 00:05:00,550 because well, as the name says they take our raw code 96 00:05:00,550 --> 00:05:04,110 and transform it into a JavaScript bundle. 97 00:05:04,110 --> 00:05:06,860 Now Webpack is the more popular one, 98 00:05:06,860 --> 00:05:10,650 but it can be really hard and confusing to set it up. 99 00:05:10,650 --> 00:05:12,950 So that's because there's a lot of stuff 100 00:05:12,950 --> 00:05:14,950 that we need to configure manually, 101 00:05:14,950 --> 00:05:17,600 in order to make it work properly. 102 00:05:17,600 --> 00:05:21,990 Parcel, on the other hand is a zero configuration bundler, 103 00:05:21,990 --> 00:05:24,700 which simply works out of the box. 104 00:05:24,700 --> 00:05:26,010 And so in this bundler, 105 00:05:26,010 --> 00:05:28,700 we don't have to write any set up code, 106 00:05:28,700 --> 00:05:30,820 which is really amazing. 107 00:05:30,820 --> 00:05:33,980 So I personally absolutely love Parcel 108 00:05:33,980 --> 00:05:35,980 and I use it all the time, 109 00:05:35,980 --> 00:05:38,390 and I think that you will love it too. 110 00:05:38,390 --> 00:05:41,010 And so, that is the JavaScript bundler 111 00:05:41,010 --> 00:05:43,373 that we gonna use later in the section. 112 00:05:44,430 --> 00:05:46,910 Now these development tools are actually 113 00:05:46,910 --> 00:05:49,940 also available on NPM. 114 00:05:49,940 --> 00:05:53,530 So just like packages that we include in our code, 115 00:05:53,530 --> 00:05:57,960 we will download and manage tools using NPM as well. 116 00:05:57,960 --> 00:06:00,530 And these tools include the live-server 117 00:06:00,530 --> 00:06:02,770 that we've been using all along, 118 00:06:02,770 --> 00:06:05,790 the Parcel bundler that we just talked about 119 00:06:05,790 --> 00:06:09,163 or Babel to transpile code back to ES5. 120 00:06:10,230 --> 00:06:14,340 All right, so this is a high level overview, 121 00:06:14,340 --> 00:06:18,310 of how we develop Modern JavaScript applications today. 122 00:06:18,310 --> 00:06:22,240 And if you ask me, this is really exciting stuff, 123 00:06:22,240 --> 00:06:24,960 because this is how professional developers 124 00:06:24,960 --> 00:06:27,570 actually write JavaScript today. 125 00:06:27,570 --> 00:06:29,830 And so in the rest of the section, 126 00:06:29,830 --> 00:06:32,710 you will take a big step in the direction 127 00:06:32,710 --> 00:06:35,473 of becoming a professional developer too.