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These are the user uploaded subtitles that are being translated: 1 1 00:00:00,930 --> 00:00:04,230 So you've already written a line or two of JavaScript, 2 2 00:00:04,230 --> 00:00:08,890 but what exactly is JavaScript and what can we do with it? 3 3 00:00:08,890 --> 00:00:10,660 Well, that's exactly what 4 4 00:00:10,660 --> 00:00:12,750 we're gonna find out in this video. 5 5 00:00:12,750 --> 00:00:14,280 And so in this lecture, 6 6 00:00:14,280 --> 00:00:17,230 we will set the stage for the rest of the course. 7 7 00:00:17,230 --> 00:00:19,150 And so it's really important that you 8 8 00:00:19,150 --> 00:00:20,883 follow this one until the end. 9 9 00:00:22,160 --> 00:00:25,680 So we can define JavaScript in many different ways. 10 10 00:00:25,680 --> 00:00:27,440 But, my definition is that 11 11 00:00:27,440 --> 00:00:30,050 it's a high level object-oriented, 12 12 00:00:30,050 --> 00:00:32,950 multi-paradigm programming language. 13 13 00:00:32,950 --> 00:00:34,290 And with that being said, 14 14 00:00:34,290 --> 00:00:36,810 can we move on to the next lecture now? 15 15 00:00:36,810 --> 00:00:39,210 Well, probably not because 16 16 00:00:39,210 --> 00:00:41,980 what does any of that actually mean? 17 17 00:00:41,980 --> 00:00:44,740 So let's deconstruct this just a little bit 18 18 00:00:44,740 --> 00:00:47,830 to at least make some sense out of this. 19 19 00:00:47,830 --> 00:00:50,660 And starting with programming language itself, 20 20 00:00:50,660 --> 00:00:53,580 a programming language is basically just a tool 21 21 00:00:53,580 --> 00:00:55,270 that allows us to write code 22 22 00:00:55,270 --> 00:00:58,910 that will instruct a computer to do something. 23 23 00:00:58,910 --> 00:01:00,800 And of course, that's our main goal 24 24 00:01:00,800 --> 00:01:03,550 of using JavaScript, right? 25 25 00:01:03,550 --> 00:01:05,100 Then I go on and say that 26 26 00:01:05,100 --> 00:01:07,460 JavaScript is a high-level language, 27 27 00:01:07,460 --> 00:01:09,780 which means that we don't have to think 28 28 00:01:09,780 --> 00:01:12,930 about a lot of complex stuff such as managing 29 29 00:01:12,930 --> 00:01:16,360 the computer's memory while it runs or program. 30 30 00:01:16,360 --> 00:01:17,460 So in JavaScript, 31 31 00:01:17,460 --> 00:01:20,090 there are a lot of so-called abstractions 32 32 00:01:20,090 --> 00:01:21,870 over all these small details 33 33 00:01:21,870 --> 00:01:23,920 that we don't want to worry about. 34 34 00:01:23,920 --> 00:01:25,040 And this makes the language 35 35 00:01:25,040 --> 00:01:28,260 a lot easier to write and to learn. 36 36 00:01:28,260 --> 00:01:31,760 Next, I say that JavaScript is object oriented. 37 37 00:01:31,760 --> 00:01:33,910 And all that means is that the language 38 38 00:01:33,910 --> 00:01:37,100 is mostly based on the concept of objects 39 39 00:01:37,100 --> 00:01:39,600 for storing most kinds of data. 40 40 00:01:39,600 --> 00:01:41,280 And of course, we will learn all about 41 41 00:01:41,280 --> 00:01:44,690 object-oriented programming throughout this course. 42 42 00:01:44,690 --> 00:01:48,490 Finally, JavaScript is also a multi-paradigm language, 43 43 00:01:48,490 --> 00:01:51,680 meaning that it's so flexible and versatile, 44 44 00:01:51,680 --> 00:01:54,940 that we can use all kinds of different programming styles, 45 45 00:01:54,940 --> 00:01:58,250 such as imperative and declarative programming. 46 46 00:01:58,250 --> 00:01:59,990 And these different styles are just 47 47 00:01:59,990 --> 00:02:03,760 different ways of structuring our code, basically. 48 48 00:02:03,760 --> 00:02:07,540 Again, you will learn all about this throughout the course. 49 49 00:02:07,540 --> 00:02:10,670 This just a first, very high level overview, 50 50 00:02:10,670 --> 00:02:13,113 but I hope it's been making sense so far. 51 51 00:02:14,640 --> 00:02:18,100 Anyway, now that we know what JavaScript actually is, 52 52 00:02:18,100 --> 00:02:20,620 at least kind of, what is the role 53 53 00:02:20,620 --> 00:02:22,720 that it plays in web development, 54 54 00:02:22,720 --> 00:02:26,340 or in other words, what do we actually use it for? 55 55 00:02:26,340 --> 00:02:27,830 And to answer that question, 56 56 00:02:27,830 --> 00:02:31,940 let's actually look at a three core technologies of the web, 57 57 00:02:31,940 --> 00:02:36,240 HTML, CSS and of course, JavaScript. 58 58 00:02:36,240 --> 00:02:39,140 So these three technologies all work together 59 59 00:02:39,140 --> 00:02:41,520 to create beautiful, interactive 60 60 00:02:41,520 --> 00:02:44,860 and dynamic websites or web applications. 61 61 00:02:44,860 --> 00:02:49,130 Now the HTML is responsible for the content of the page. 62 62 00:02:49,130 --> 00:02:51,880 So the text, the images, the buttons, 63 63 00:02:51,880 --> 00:02:54,480 and all the contents that you see on the webpage 64 64 00:02:54,480 --> 00:02:57,150 is always written in HTML. 65 65 00:02:57,150 --> 00:03:00,040 Then the CSS is responsible for the 66 66 00:03:00,040 --> 00:03:02,160 line:15% presentation of that content. 67 67 00:03:02,160 --> 00:03:05,000 So basically for styling and for laying out 68 68 00:03:05,000 --> 00:03:07,330 the elements on a webpage. 69 69 00:03:07,330 --> 00:03:10,300 And then, finally, JavaScript is the real 70 70 00:03:10,300 --> 00:03:12,920 line:15% programming language of the internet. 71 71 00:03:12,920 --> 00:03:15,540 And it allows developers to add dynamic 72 72 00:03:15,540 --> 00:03:19,470 and interactive effects to any webpage. 73 73 00:03:19,470 --> 00:03:23,110 We also use it to manipulate the content or the CSS, 74 74 00:03:23,110 --> 00:03:25,420 load data from remote servers 75 75 00:03:25,420 --> 00:03:29,310 and really build entire applications in the browser, 76 76 00:03:29,310 --> 00:03:32,530 which we then call web applications. 77 77 00:03:32,530 --> 00:03:35,340 Now, we can also use the analogy of nouns, 78 78 00:03:35,340 --> 00:03:38,300 adjectives, and verbs to make this separation 79 79 00:03:38,300 --> 00:03:40,783 of roles a bit easier to understand. 80 80 00:03:41,670 --> 00:03:45,290 So in this analogy, HTML represents the nouns. 81 81 00:03:45,290 --> 00:03:49,870 For example, saying that the P element is a paragraph. 82 82 00:03:49,870 --> 00:03:53,070 And so paragraph is the noun here. 83 83 00:03:53,070 --> 00:03:55,390 The CSS then, is the adjective, 84 84 00:03:55,390 --> 00:03:57,660 because it describes the noun. 85 85 00:03:57,660 --> 00:04:02,510 Like this piece of CSS saying the paragraph text is red. 86 86 00:04:02,510 --> 00:04:06,470 And so here, red is the adjective describing the noun. 87 87 00:04:06,470 --> 00:04:10,110 And finally JavaScript is, of course, the verb, 88 88 00:04:10,110 --> 00:04:12,910 like saying hide the paragraph. 89 89 00:04:12,910 --> 00:04:16,960 And so here we are doing something and so we have a verb. 90 90 00:04:16,960 --> 00:04:17,800 Okay? 91 91 00:04:17,800 --> 00:04:19,390 Does that make sense? 92 92 00:04:19,390 --> 00:04:21,140 Now, since we've been talking a lot 93 93 00:04:21,140 --> 00:04:24,580 about dynamic effects and web applications here, 94 94 00:04:24,580 --> 00:04:27,640 let's now actually take a look at a real example 95 95 00:04:27,640 --> 00:04:31,463 to make it even more clear what JavaScript is capable of. 96 96 00:04:33,060 --> 00:04:36,760 And so this is the Twitter web application on twitter.com 97 97 00:04:36,760 --> 00:04:38,440 and there is a lot happening 98 98 00:04:38,440 --> 00:04:41,480 as we open a profile page like this one. 99 99 00:04:41,480 --> 00:04:45,290 And so I thought that this was a very cool example. 100 100 00:04:45,290 --> 00:04:46,850 So right off the bat, 101 101 00:04:46,850 --> 00:04:48,080 you see that there are these 102 102 00:04:48,080 --> 00:04:50,450 two rotating spinners on the page, 103 103 00:04:50,450 --> 00:04:53,770 meaning that JavaScript is probably loading some data 104 104 00:04:53,770 --> 00:04:56,880 from the Twitter service in the background. 105 105 00:04:56,880 --> 00:04:59,150 Then, as the data arrives, 106 106 00:04:59,150 --> 00:05:01,370 JavaScript hides these spinners, 107 107 00:05:01,370 --> 00:05:03,703 and instead show us the loaded content. 108 108 00:05:04,570 --> 00:05:06,350 So this is a very cool example 109 109 00:05:06,350 --> 00:05:10,370 of manipulating styles and content, right? 110 110 00:05:10,370 --> 00:05:14,100 But there's also some simpler dynamic effect on this page, 111 111 00:05:14,100 --> 00:05:16,560 like JavaScript showing the tweet box 112 112 00:05:16,560 --> 00:05:18,530 whenever we hit the tweet button 113 113 00:05:18,530 --> 00:05:22,630 and then hides it as we click outside of that box. 114 114 00:05:22,630 --> 00:05:24,900 And finally, JavaScript also displays 115 115 00:05:24,900 --> 00:05:27,180 this really nice user information 116 116 00:05:27,180 --> 00:05:30,610 as we hover our mouse over any user on Twitter. 117 117 00:05:30,610 --> 00:05:34,440 And it probably also loads this data on the fly. 118 118 00:05:34,440 --> 00:05:37,040 So a lot of cool stuff going on here, 119 119 00:05:37,040 --> 00:05:39,640 and it's all powered by JavaScript. 120 120 00:05:39,640 --> 00:05:41,450 How cool is that? 121 121 00:05:41,450 --> 00:05:43,830 And in fact, by the end of the course, 122 122 00:05:43,830 --> 00:05:45,550 you will actually know how to use 123 123 00:05:45,550 --> 00:05:48,340 all of these techniques that we just saw here. 124 124 00:05:48,340 --> 00:05:50,040 And so I hope that this makes you 125 125 00:05:50,040 --> 00:05:53,143 even more excited about all the content ahead. 126 126 00:05:54,770 --> 00:05:56,670 Alright, now that we saw what 127 127 00:05:56,670 --> 00:06:00,730 JavaScript is really capable of, let's quickly recap, 128 128 00:06:00,730 --> 00:06:03,090 and also look at other cool stuff 129 129 00:06:03,090 --> 00:06:06,720 that we can build with the power of JavaScript. 130 130 00:06:06,720 --> 00:06:08,460 So as you already know, 131 131 00:06:08,460 --> 00:06:12,230 Java script allows us to add dynamic effects to pages. 132 132 00:06:12,230 --> 00:06:14,600 And in fact, to build entire 133 133 00:06:14,600 --> 00:06:17,220 web applications in the browser, 134 134 00:06:17,220 --> 00:06:19,920 and these applications feel almost like the apps 135 135 00:06:19,920 --> 00:06:23,960 that we use on our computers and phones every single day. 136 136 00:06:23,960 --> 00:06:25,550 So we can say that JavaScript 137 137 00:06:25,550 --> 00:06:28,160 is what made modern web development, 138 138 00:06:28,160 --> 00:06:30,380 and really the whole modern web itself 139 139 00:06:30,380 --> 00:06:32,750 possible in the first place. 140 140 00:06:32,750 --> 00:06:34,690 Now, if you're already somewhat familiar 141 141 00:06:34,690 --> 00:06:37,170 with the web development industry, 142 142 00:06:37,170 --> 00:06:39,830 you probably heard of modern JavaScript libraries 143 143 00:06:39,830 --> 00:06:44,830 and frameworks such as React, Angular or Vue, right? 144 144 00:06:45,180 --> 00:06:48,500 And if you didn't, that's absolutely no problem. 145 145 00:06:48,500 --> 00:06:51,650 All you need to know is that these are basically tools 146 146 00:06:51,650 --> 00:06:54,970 that make writing modern, large scale web applications, 147 147 00:06:54,970 --> 00:06:57,350 a lot easier and faster. 148 148 00:06:57,350 --> 00:07:00,270 Now what matters here, is that all these frameworks 149 149 00:07:00,270 --> 00:07:05,260 and libraries are still 100% based on JavaScript. 150 150 00:07:05,260 --> 00:07:07,980 And what this means is that you should become really, 151 151 00:07:07,980 --> 00:07:09,802 really good at JavaScript before learning 152 152 00:07:09,802 --> 00:07:13,100 and using any of these frameworks, 153 153 00:07:13,100 --> 00:07:16,000 and not just jump into your first framework 154 154 00:07:16,000 --> 00:07:19,880 after you know how to write, like, 10 lines of JavaScript. 155 155 00:07:19,880 --> 00:07:21,200 Okay? 156 156 00:07:21,200 --> 00:07:23,340 Also your library of choice 157 157 00:07:23,340 --> 00:07:26,670 might not always be as popular as it is today. 158 158 00:07:26,670 --> 00:07:30,450 And the best way to be prepared is, you guessed it, 159 159 00:07:30,450 --> 00:07:33,400 becoming really good at JavaScript, 160 160 00:07:33,400 --> 00:07:37,520 because then you can easily learn whatever is popular next. 161 161 00:07:37,520 --> 00:07:39,740 So no matter what anyone tells you, 162 162 00:07:39,740 --> 00:07:41,610 learning JavaScript properly 163 163 00:07:41,610 --> 00:07:44,650 is the single best investment that you can make 164 164 00:07:44,650 --> 00:07:47,980 in your web development career right now. 165 165 00:07:47,980 --> 00:07:50,950 Now the JavaScript language and the web browser 166 166 00:07:50,950 --> 00:07:53,260 are actually two separate things. 167 167 00:07:53,260 --> 00:07:55,500 And what that means is that JavaScript 168 168 00:07:55,500 --> 00:07:58,740 can also run outside of web browsers. 169 169 00:07:58,740 --> 00:08:02,970 For example, it's possible to use JavaScript on a web server 170 170 00:08:02,970 --> 00:08:06,770 using a very popular technology called Node.js, 171 171 00:08:06,770 --> 00:08:09,430 which doesn't need any browser at all. 172 172 00:08:09,430 --> 00:08:13,330 And this allows us to create so-called backend applications, 173 173 00:08:13,330 --> 00:08:16,390 which are simply applications that run on a web server 174 174 00:08:16,390 --> 00:08:20,150 and interact with databases and stuff like that. 175 175 00:08:20,150 --> 00:08:23,450 On the other hand, when we use JavaScript in the browser, 176 176 00:08:23,450 --> 00:08:27,000 we create so-called front end applications. 177 177 00:08:27,000 --> 00:08:30,040 So in this course, we will learn the ins and outs 178 178 00:08:30,040 --> 00:08:32,410 of the JavaScript language itself, 179 179 00:08:32,410 --> 00:08:35,710 and of course also how to use it in the browser 180 180 00:08:35,710 --> 00:08:38,400 in order to create all these amazing effects 181 181 00:08:38,400 --> 00:08:40,260 that we've been talking about. 182 182 00:08:40,260 --> 00:08:41,530 So basically we're going to be 183 183 00:08:41,530 --> 00:08:44,720 building front-end web applications. 184 184 00:08:44,720 --> 00:08:45,730 And in the future, 185 185 00:08:45,730 --> 00:08:48,860 I might also add a section about Node.js 186 186 00:08:48,860 --> 00:08:50,380 at the end of this course, 187 187 00:08:50,380 --> 00:08:53,410 so that you can get a sense of how we can use JavaScript 188 188 00:08:53,410 --> 00:08:56,573 outside of the browser environment as well. 189 189 00:08:57,550 --> 00:08:58,383 All right. 190 190 00:08:58,383 --> 00:09:00,233 And now, just to finish, I want to mention 191 191 00:09:00,233 --> 00:09:03,110 that we can actually also use JavaScript 192 192 00:09:03,110 --> 00:09:06,070 line:15% to build kind of native mobile applications, 193 193 00:09:06,070 --> 00:09:08,820 line:15% as well as native desktop applications 194 194 00:09:08,820 --> 00:09:12,500 line:15% for any phone and computer operating system out there. 195 195 00:09:12,500 --> 00:09:15,600 That's because of modern tools like React Native, 196 196 00:09:15,600 --> 00:09:19,350 the Ionic framework and tools like Electron. 197 197 00:09:19,350 --> 00:09:22,500 These have completely changed the whole development industry 198 198 00:09:22,500 --> 00:09:24,070 over the last couple of years, 199 199 00:09:24,070 --> 00:09:27,960 making things possible that were never possible before. 200 200 00:09:27,960 --> 00:09:30,900 So as you can see, there's almost nothing 201 201 00:09:30,900 --> 00:09:33,070 that you can't build after becoming 202 202 00:09:33,070 --> 00:09:35,020 really good at JavaScript, 203 203 00:09:35,020 --> 00:09:39,260 which if you think about it, is really kind of mind-blowing. 204 204 00:09:39,260 --> 00:09:43,233 It's just amazing, because the possibilities are so endless. 205 205 00:09:44,200 --> 00:09:45,033 Okay. 206 206 00:09:45,033 --> 00:09:46,540 And now to finish this lecture, 207 207 00:09:46,540 --> 00:09:49,840 I want to briefly talk about JavaScript releases 208 208 00:09:49,840 --> 00:09:52,400 or versions, as you might call them. 209 209 00:09:52,400 --> 00:09:55,120 We will come back to this topic by the end of the section 210 210 00:09:55,120 --> 00:09:57,240 because it's super important, 211 211 00:09:57,240 --> 00:10:00,360 but it's also a good idea to get a first overview 212 212 00:10:00,360 --> 00:10:03,470 of JavaScript releases at this point. 213 213 00:10:03,470 --> 00:10:06,140 Anyway, to make a long story short, 214 214 00:10:06,140 --> 00:10:10,280 there has been a huge update to the language in 2015, 215 215 00:10:10,280 --> 00:10:13,020 which is officially called ES2015, 216 216 00:10:13,020 --> 00:10:15,440 but most people just call it ES6, 217 217 00:10:15,440 --> 00:10:19,100 simply because it was released after ES5. 218 218 00:10:19,100 --> 00:10:23,090 And by the way, E. S stands for ECMAScript. 219 219 00:10:23,090 --> 00:10:25,180 Now after ES2015, 220 220 00:10:25,180 --> 00:10:27,410 there is now a yearly new release 221 221 00:10:27,410 --> 00:10:29,940 with a couple of new JavaScript features. 222 222 00:10:29,940 --> 00:10:32,870 In all of these new releases or versions, 223 223 00:10:32,870 --> 00:10:37,870 starting from ES2015, is what we call modern JavaScript. 224 224 00:10:38,100 --> 00:10:40,530 But, why am I telling you all this? 225 225 00:10:40,530 --> 00:10:42,870 Well, it's simply because in this course, 226 226 00:10:42,870 --> 00:10:44,890 I'm gonna teach you a modern JavaScript, 227 227 00:10:44,890 --> 00:10:46,400 right from the beginning. 228 228 00:10:46,400 --> 00:10:49,860 And I wanted to make that very clear right from the start. 229 229 00:10:49,860 --> 00:10:51,840 However, I'm also convinced that 230 230 00:10:51,840 --> 00:10:56,840 you need to understand what came before ES2015, so ES5. 231 231 00:10:57,360 --> 00:11:01,750 And so I will also show you what's important of ES5. 232 232 00:11:01,750 --> 00:11:03,880 The reason for that is in a complete video 233 233 00:11:03,880 --> 00:11:07,690 about JavaScript releases at the end of this section, 234 234 00:11:07,690 --> 00:11:11,830 because now I no longer want to bore you with theory. 235 235 00:11:11,830 --> 00:11:15,383 So instead, let's now finally get started. 20814