1 00:00:02,250 --> 00:00:05,660 So I'm gonna brand new empty project here, 2 00:00:05,660 --> 00:00:06,900 an empty folder, 3 00:00:06,900 --> 00:00:09,060 open up in Visual Studio code, 4 00:00:09,060 --> 00:00:10,800 the IDE I'm using here. 5 00:00:10,800 --> 00:00:11,633 And in there, 6 00:00:11,633 --> 00:00:14,380 we're going to write some first Deno code. 7 00:00:14,380 --> 00:00:17,280 Now, here's one important disclaimer, 8 00:00:17,280 --> 00:00:19,870 one important prerequisite, 9 00:00:19,870 --> 00:00:24,020 you should not dive into this module right away. 10 00:00:24,020 --> 00:00:28,340 I do expect that you went through the node course first, 11 00:00:28,340 --> 00:00:30,710 maybe not through all sections there, 12 00:00:30,710 --> 00:00:33,410 but definitely through all the basic sections, 13 00:00:33,410 --> 00:00:36,010 so that you know why we use node, 14 00:00:36,010 --> 00:00:38,040 how we write node code, 15 00:00:38,040 --> 00:00:40,530 how we can spin up a node web server, 16 00:00:40,530 --> 00:00:43,660 so that you know about the Express framework. 17 00:00:43,660 --> 00:00:47,050 All that knowledge is required for this module, 18 00:00:47,050 --> 00:00:51,990 because I'm teaching Deno for people that already know node, 19 00:00:51,990 --> 00:00:53,370 at least a bit. 20 00:00:53,370 --> 00:00:54,900 That's important. 21 00:00:54,900 --> 00:00:57,540 In addition, I mentioned that with Deno 22 00:00:57,540 --> 00:01:01,160 you will be able to execute TypeScript code 23 00:01:01,160 --> 00:01:02,930 Therefore, it will help a lot. 24 00:01:02,930 --> 00:01:04,060 If you went through that 25 00:01:04,060 --> 00:01:07,120 TypeScript module in this course, first, 26 00:01:07,120 --> 00:01:08,960 that's just another node. 27 00:01:08,960 --> 00:01:13,280 Also check out the modern JavaScript with node module first 28 00:01:13,280 --> 00:01:15,290 before you go through this module. 29 00:01:15,290 --> 00:01:17,560 With that all out of the way, though, 30 00:01:17,560 --> 00:01:19,570 you should have an easy time following along. 31 00:01:19,570 --> 00:01:22,879 And therefore let's write our first Deno code. 32 00:01:22,879 --> 00:01:24,480 Now, as I mentioned, 33 00:01:24,480 --> 00:01:26,990 it's up to us whenever you want to write this code 34 00:01:26,990 --> 00:01:29,400 with JavaScript or with TypeScript. 35 00:01:29,400 --> 00:01:31,900 But since steno does support TypeScript, 36 00:01:31,900 --> 00:01:34,610 and since this is a core difference to note 37 00:01:34,610 --> 00:01:37,570 that Deno has this built in TypeScript compiler, 38 00:01:37,570 --> 00:01:40,630 and we don't need to compile the code ahead of time. 39 00:01:40,630 --> 00:01:42,080 Since that is all the case, 40 00:01:42,080 --> 00:01:44,370 let's write some TypeScript code. 41 00:01:44,370 --> 00:01:46,810 And hence here I'm adding an app.ts file. 42 00:01:46,810 --> 00:01:48,420 The name is fully up to you, though, 43 00:01:48,420 --> 00:01:49,920 I'm just using .ts 44 00:01:49,920 --> 00:01:53,050 because I will write some TypeScript code in there. 45 00:01:53,050 --> 00:01:56,070 And here, our first basic Deno code 46 00:01:56,070 --> 00:01:58,440 could be code that we can almost run 47 00:01:58,440 --> 00:02:01,314 like this with node js As well, 48 00:02:01,314 --> 00:02:03,860 I'm going to define a message variable, 49 00:02:03,860 --> 00:02:05,720 which will be of type string. 50 00:02:05,720 --> 00:02:08,780 So this is how I assign a type with TypeScript, 51 00:02:08,780 --> 00:02:10,090 I'm making it clear that 52 00:02:10,090 --> 00:02:12,680 this should contain a string eventually, 53 00:02:12,680 --> 00:02:15,913 then I'm assigning such a string value. 54 00:02:15,913 --> 00:02:18,680 And then I console log it. 55 00:02:18,680 --> 00:02:20,490 Now it's needless to say that 56 00:02:20,490 --> 00:02:24,086 we could have merged these two lines of code into one line. 57 00:02:24,086 --> 00:02:26,250 But I want to show you 58 00:02:26,250 --> 00:02:28,760 that we can use TypeScript features here. 59 00:02:28,760 --> 00:02:31,440 That's why I'm going for two lines. 60 00:02:31,440 --> 00:02:33,350 Now, this is no fancy app. 61 00:02:33,350 --> 00:02:34,800 This is no web server. 62 00:02:34,800 --> 00:02:36,160 But this is some code, 63 00:02:36,160 --> 00:02:39,690 which we will be able to execute with Deno. 64 00:02:39,690 --> 00:02:41,630 So with that saved, 65 00:02:41,630 --> 00:02:43,760 we can now open up the terminal. 66 00:02:43,760 --> 00:02:46,890 And here I'm using the one integrated into the IDE. 67 00:02:46,890 --> 00:02:50,080 And we can execute our app.ts file with Deno, 68 00:02:50,080 --> 00:02:53,370 however, not with just Deno and then the file name, 69 00:02:53,370 --> 00:02:57,060 but instead with Deno, run app.ts. 70 00:02:57,060 --> 00:02:58,670 So that's a difference to note 71 00:02:58,670 --> 00:03:01,280 with node with just execute a file with node 72 00:03:01,280 --> 00:03:03,290 and then a file name, with Deno, 73 00:03:03,290 --> 00:03:06,390 it's Deno run, and then the file name. 74 00:03:06,390 --> 00:03:08,030 Other than that it's quite similar though, 75 00:03:08,030 --> 00:03:10,608 this will now execute this file with Deno. 76 00:03:10,608 --> 00:03:12,360 And you see, first of all, 77 00:03:12,360 --> 00:03:14,060 it compiles to code 78 00:03:14,060 --> 00:03:16,350 from TypeScript to JavaScript, you could say. 79 00:03:16,350 --> 00:03:17,510 And then the 80 00:03:17,510 --> 00:03:19,380 we ate JavaScript engine 81 00:03:19,380 --> 00:03:21,580 that is wrapped by Deno goes ahead, 82 00:03:21,580 --> 00:03:23,400 executes the JavaScript code, 83 00:03:23,400 --> 00:03:26,230 and therefore prints Hi there. 84 00:03:26,230 --> 00:03:27,920 So this works. 85 00:03:27,920 --> 00:03:29,580 If I run this again, by the way, 86 00:03:29,580 --> 00:03:32,710 you will notice that the compilation step is skipped, 87 00:03:32,710 --> 00:03:35,200 because it caches the compiled code. 88 00:03:35,200 --> 00:03:37,430 And if you didn't change the code at all, 89 00:03:37,430 --> 00:03:40,350 it will just reuse that already compiled code 90 00:03:40,350 --> 00:03:42,520 to run the script again. 91 00:03:42,520 --> 00:03:45,910 So this is now a very simple first app, 92 00:03:45,910 --> 00:03:48,260 if we want to call it an app, 93 00:03:48,260 --> 00:03:50,980 which we can execute with Deno. 94 00:03:50,980 --> 00:03:54,540 Arguably not too fancy, but a nice start. 95 00:03:54,540 --> 00:03:59,116 Now before we start writing some web server code with Deno 96 00:03:59,116 --> 00:04:01,860 let's see what else we can do. 97 00:04:01,860 --> 00:04:04,860 Let's see what is baked into Deno. 98 00:04:04,860 --> 00:04:06,639 Because for node, 99 00:04:06,639 --> 00:04:09,810 if we dive into the node API docs, 100 00:04:09,810 --> 00:04:13,660 we have all those core modules that are built into node. 101 00:04:13,660 --> 00:04:16,293 Now let's see if there is an equivalent for Deno.