1 00:00:02,060 --> 00:00:03,950 Now that's it for this section. 2 00:00:03,950 --> 00:00:08,430 And this was definitely not a small or easy section. 3 00:00:08,430 --> 00:00:10,560 We had lots of new concepts 4 00:00:10,560 --> 00:00:14,360 and it's very likely that you're not 100% on board 5 00:00:14,360 --> 00:00:16,650 with all those concepts yet. 6 00:00:16,650 --> 00:00:19,070 That's totally normal though. 7 00:00:19,070 --> 00:00:20,562 These are a lot of concepts 8 00:00:20,562 --> 00:00:23,800 and pretty advanced concepts too, 9 00:00:23,800 --> 00:00:25,740 but I wanted to get them out of the way, 10 00:00:25,740 --> 00:00:28,970 because we'll see them throughout the rest of the course. 11 00:00:28,970 --> 00:00:31,800 And therefore, of course, as we start using them there, 12 00:00:31,800 --> 00:00:34,420 also in more realistic examples, 13 00:00:34,420 --> 00:00:37,100 things also will become clearer. 14 00:00:37,100 --> 00:00:40,230 It was important to introduce them now though, 15 00:00:40,230 --> 00:00:43,920 so that later sections can focus on different parts 16 00:00:43,920 --> 00:00:47,053 and you have at least seen those concepts already then. 17 00:00:47,890 --> 00:00:50,090 We did learn about functions 18 00:00:50,090 --> 00:00:52,700 and default parameter values, 19 00:00:52,700 --> 00:00:57,040 hence turning these parameters into optional parameters. 20 00:00:57,040 --> 00:01:00,700 And we learned about the rest parameter operator here, 21 00:01:00,700 --> 00:01:05,330 the three dots that allows us to past in a list of values 22 00:01:05,330 --> 00:01:10,330 instead of a fixed number of values or an array. 23 00:01:10,490 --> 00:01:12,580 We also learned about the spread operator, 24 00:01:12,580 --> 00:01:13,940 which is the opposite, 25 00:01:13,940 --> 00:01:17,210 which allows us to pull out all the values off an array 26 00:01:17,210 --> 00:01:21,410 or object in places where a list of values 27 00:01:21,410 --> 00:01:24,440 or a list of key value pairs is needed 28 00:01:24,440 --> 00:01:27,530 instead of the full array or object. 29 00:01:27,530 --> 00:01:30,560 These were some things we learned about functions. 30 00:01:30,560 --> 00:01:33,720 We also learned about that template literal syntax, 31 00:01:33,720 --> 00:01:37,450 which allows us to construct strings with placeholders. 32 00:01:37,450 --> 00:01:40,710 And hence it gives us a way of constructing longer strings 33 00:01:40,710 --> 00:01:43,970 with dynamic values in a more convenient way 34 00:01:43,970 --> 00:01:47,310 than having to concatenate strings and values 35 00:01:47,310 --> 00:01:49,630 with the plus operator. 36 00:01:49,630 --> 00:01:53,420 Now, we also did dive into some behind the scenes things 37 00:01:53,420 --> 00:01:54,810 thereafter. 38 00:01:54,810 --> 00:01:58,410 We had a look at reference where this primitive values 39 00:01:58,410 --> 00:02:01,430 and that objects are reference values, 40 00:02:01,430 --> 00:02:03,470 and that those values are stored 41 00:02:03,470 --> 00:02:05,810 in a special kind of memory, 42 00:02:05,810 --> 00:02:08,880 which actually leads JavaScript to just store 43 00:02:08,880 --> 00:02:10,789 the address of that space 44 00:02:10,789 --> 00:02:13,310 and memory in constants or variables 45 00:02:13,310 --> 00:02:15,900 instead of the value as a whole. 46 00:02:15,900 --> 00:02:20,520 That's why we can edit such values stored in a constant 47 00:02:20,520 --> 00:02:22,420 without facing an error, 48 00:02:22,420 --> 00:02:24,240 because we're not actually editing 49 00:02:24,240 --> 00:02:25,980 the value in the constant, 50 00:02:25,980 --> 00:02:28,430 but the value stored in memory. 51 00:02:28,430 --> 00:02:32,160 The value in the constant is just the address of that value 52 00:02:32,160 --> 00:02:35,383 and memory, and that address didn't change. 53 00:02:36,560 --> 00:02:39,180 We had a look at a couple of related concepts 54 00:02:39,180 --> 00:02:41,450 and you also learned that you can again use 55 00:02:41,450 --> 00:02:45,600 the spread operator to still create copies of objects 56 00:02:45,600 --> 00:02:50,370 or erase with ease in case you need to fully copy an object 57 00:02:50,370 --> 00:02:51,203 or array, 58 00:02:51,203 --> 00:02:54,110 and you don't want to work with that existing object 59 00:02:54,110 --> 00:02:56,450 or array in memory, for example, 60 00:02:56,450 --> 00:03:00,493 to avoid unwanted mutation of that object or array, 61 00:03:00,493 --> 00:03:02,543 as we had it in this example. 62 00:03:04,570 --> 00:03:07,500 We also explored errors. 63 00:03:07,500 --> 00:03:10,050 Error handling is something which matters. 64 00:03:10,050 --> 00:03:12,950 And with try-catch you can handle errors 65 00:03:12,950 --> 00:03:15,210 in a fine grained way 66 00:03:15,210 --> 00:03:19,060 where you have full control over which code might fail 67 00:03:19,060 --> 00:03:21,963 and how you want to handle that failure. 68 00:03:23,070 --> 00:03:26,100 We also had a closer look at objects again. 69 00:03:26,100 --> 00:03:27,477 We explored classes 70 00:03:27,477 --> 00:03:30,630 which allow us to create our own blueprints 71 00:03:30,630 --> 00:03:32,450 for our own objects, 72 00:03:32,450 --> 00:03:35,760 where we can use the constructor to tell JavaScript 73 00:03:35,760 --> 00:03:39,210 how objects based on that class should be created 74 00:03:39,210 --> 00:03:41,660 and which properties they should have. 75 00:03:41,660 --> 00:03:44,150 And we learned that we can add methods. 76 00:03:44,150 --> 00:03:46,814 Here that this keyword is also important 77 00:03:46,814 --> 00:03:51,180 because this keyword gives us access to the object 78 00:03:51,180 --> 00:03:53,040 that's about to be created, 79 00:03:53,040 --> 00:03:56,680 or that was created in case of methods. 80 00:03:56,680 --> 00:03:59,870 And then we can instantiate classes, 81 00:03:59,870 --> 00:04:03,301 create concrete objects based on the blueprint 82 00:04:03,301 --> 00:04:05,970 by executing the class as a function 83 00:04:05,970 --> 00:04:07,913 and adding the new keyword. 84 00:04:09,370 --> 00:04:13,020 Last but not least, but definitely also very important, 85 00:04:13,020 --> 00:04:15,600 we had a look at async code. 86 00:04:15,600 --> 00:04:17,529 And you've learned that some operations 87 00:04:17,529 --> 00:04:19,760 simply can take a bit longer 88 00:04:19,760 --> 00:04:22,120 and therefore you might want to perform them 89 00:04:22,120 --> 00:04:24,029 in an asynchronous way, 90 00:04:24,029 --> 00:04:27,160 either with help of a callback function 91 00:04:27,160 --> 00:04:29,740 or with help of a promise. 92 00:04:29,740 --> 00:04:31,870 And when working with promises, 93 00:04:31,870 --> 00:04:34,310 you can also turn your overall function 94 00:04:34,310 --> 00:04:38,220 that wraps the async code into an async function, 95 00:04:38,220 --> 00:04:40,370 and then use the await keyword 96 00:04:40,370 --> 00:04:44,240 to go back to more synchronous looking code, 97 00:04:44,240 --> 00:04:46,340 even though it's transformed under the hood, 98 00:04:46,340 --> 00:04:47,173 as you learned. 99 00:04:48,210 --> 00:04:52,290 We also had a look at how error handling could work there, 100 00:04:52,290 --> 00:04:54,140 but also as mentioned before, 101 00:04:54,140 --> 00:04:56,350 we are going to see async code 102 00:04:56,350 --> 00:05:00,100 and promises in action again later in the course, 103 00:05:00,100 --> 00:05:02,883 also once we start working with databases. 104 00:05:03,750 --> 00:05:06,850 And, therefore, we had plenty of new content here, 105 00:05:06,850 --> 00:05:11,500 definitely also check out the written guide and cheat sheet, 106 00:05:11,500 --> 00:05:13,840 which you'll find attached to the last lecture 107 00:05:13,840 --> 00:05:15,910 of this course section. 108 00:05:15,910 --> 00:05:18,660 But definitely also don't feel overwhelmed, 109 00:05:18,660 --> 00:05:21,010 instead we're going to see all these concepts 110 00:05:21,010 --> 00:05:23,603 in action again later in the course.