1 00:00:02,380 --> 00:00:08,760 So how could we fix this here and find an object in an array index of doesn't work? 2 00:00:08,830 --> 00:00:16,140 Well you have another method or two other methods which you can use in such a situation. So let's say 3 00:00:16,290 --> 00:00:18,600 Manuel is the person I want to find, 4 00:00:18,600 --> 00:00:22,560 well then you can use person data and then there is a find method, 5 00:00:22,560 --> 00:00:25,950 that's also a method which is available on every real array 6 00:00:25,950 --> 00:00:27,930 and now find is an interesting method. 7 00:00:27,960 --> 00:00:34,110 It takes an argument but the argument it takes is actually another function. 8 00:00:34,110 --> 00:00:39,900 Now this is a typical use case for an anonymous function, though of course you could also define a function 9 00:00:39,900 --> 00:00:42,810 somewhere and then just pass in a reference to that function, 10 00:00:42,840 --> 00:00:48,090 so the function name but since this often is a function which you only need to run in this place and 11 00:00:48,090 --> 00:00:53,710 which you never call from anywhere else in your code, this is a perfect scenario for an anonymous function. 12 00:00:53,710 --> 00:00:56,610 Now of course it's not just a function like this which does nothing, 13 00:00:56,670 --> 00:01:01,390 instead it's a function that can accept up to three arguments. 14 00:01:01,530 --> 00:01:06,860 The first argument will always be a single object of that array, 15 00:01:06,900 --> 00:01:08,590 so we could name this person, 16 00:01:08,610 --> 00:01:10,570 you can choose any name you want here. 17 00:01:10,590 --> 00:01:15,140 The second argument will always be the index of that single element, 18 00:01:15,210 --> 00:01:18,920 so you could name it index or idx or whatever you want. 19 00:01:19,020 --> 00:01:22,620 The third argument will be the full array, 20 00:01:22,620 --> 00:01:29,190 so persons for example. Now who is calling that function? Javascript that will call it for you 21 00:01:29,220 --> 00:01:35,910 so to say, find executes on this array and what it does is it executes this anonymous function which you 22 00:01:35,910 --> 00:01:36,710 pass to it 23 00:01:36,720 --> 00:01:42,120 or this function in general what you pass to it on every element in person data. 24 00:01:42,120 --> 00:01:49,050 So it will execute this function here on every element in person data and will then for every execution 25 00:01:49,050 --> 00:01:49,870 pass in 26 00:01:49,890 --> 00:01:55,820 that element it's currently looking at, then the index of that element and then the full array. 27 00:01:55,860 --> 00:02:01,110 Now of course, you can also use find on any array, even if it's an array full of numbers or text, it's 28 00:02:01,110 --> 00:02:07,320 not restricted to arrays full of objects, that's just a use case where it's particularly helpful because 29 00:02:07,320 --> 00:02:12,000 it can help us identify an object or a value if it's a reference value 30 00:02:12,020 --> 00:02:18,680 because for primitive values, often index of helps us get what we want, though that of course returns the 31 00:02:18,680 --> 00:02:19,250 index 32 00:02:19,280 --> 00:02:23,000 but then we could use that index to easily access the value behind that index, 33 00:02:23,000 --> 00:02:23,720 right? 34 00:02:23,870 --> 00:02:24,770 But back to find, 35 00:02:24,770 --> 00:02:31,430 so we execute this on every item in person data and it then expects that this function which you pass 36 00:02:31,430 --> 00:02:35,990 to find returns true for the element you're looking for, 37 00:02:36,140 --> 00:02:40,680 so for the element you are trying to find and false for all other elements. 38 00:02:40,700 --> 00:02:44,090 So in here, we have to return something and that should be a boolean, 39 00:02:44,090 --> 00:02:46,870 so typically in here you have some kind of comparison. 40 00:02:47,060 --> 00:02:53,690 So we could compare person.name because we know we execute this on an array of person data, 41 00:02:53,720 --> 00:02:57,410 so we have a bunch of objects in there which have a name property 42 00:02:57,410 --> 00:02:59,660 and this is a single element of the array, 43 00:02:59,660 --> 00:03:00,530 don't forget that 44 00:03:00,620 --> 00:03:08,240 so it will be an object with a name property and we can check whether that is equal to Manuel for example 45 00:03:08,240 --> 00:03:09,370 in this case 46 00:03:09,620 --> 00:03:14,780 and this should find us that one object where the name is Manuel. 47 00:03:14,780 --> 00:03:20,480 Now if you have multiple objects with a name of Manuel, it will still stop after the first hit, just like 48 00:03:20,480 --> 00:03:27,350 index of, it will stop after that and not return all fitting elements but only the first one. So find 49 00:03:27,350 --> 00:03:33,380 returns us Manuel, here therefore I'm not even using that index or that entire array and quite often, 50 00:03:33,380 --> 00:03:38,020 you'll not need that but if you need it for some reason, in that function, you have it available and therefore 51 00:03:38,020 --> 00:03:44,960 now if I console log Manuel here, we hopefully console log a Javascript object which is having a 52 00:03:44,960 --> 00:03:46,490 name of Manuel. 53 00:03:46,580 --> 00:03:49,970 So if we now reload, that's looking good. 54 00:03:49,970 --> 00:03:55,060 Now one important note about find, it returns the same object as you have in the array here, 55 00:03:55,070 --> 00:03:57,660 it does not copy it or anything like that. 56 00:03:57,710 --> 00:04:03,860 So if I then would manipulate Manuel's name here and set it to Anna 57 00:04:03,890 --> 00:04:11,720 which is pretty drastic change I guess but let's still do it, then I will not only see that here when 58 00:04:11,720 --> 00:04:18,950 I log Manuel but also if I log the entire person data array again. If I do that though and I reload, 59 00:04:18,950 --> 00:04:25,010 you see here we have Anna but we also have that here in the array because we're working with the same 60 00:04:25,190 --> 00:04:29,090 reference value, with the exact same object, that's important to understand, 61 00:04:29,150 --> 00:04:32,160 find does not create a copy. 62 00:04:32,170 --> 00:04:41,780 Now just like find, you also have find index, so you can get Anna or max index here by using person data 63 00:04:42,050 --> 00:04:46,070 find index and then it takes the exact same function, 64 00:04:46,160 --> 00:04:48,050 so exactly in the same way, 65 00:04:48,050 --> 00:04:54,110 now I just want to look for Max here and the difference is that it will not return the matching item 66 00:04:54,220 --> 00:04:57,380 of the array but the index of that item. 67 00:04:57,380 --> 00:05:05,900 So if I now console log max index down there, we should see 0 because that max object is the first element 68 00:05:05,930 --> 00:05:08,910 of that array and therefore has an index of 0. 69 00:05:08,920 --> 00:05:13,970 So if we save that, reload, indeed here we see 0 being printed 70 00:05:14,000 --> 00:05:15,420 so that also works. 71 00:05:15,470 --> 00:05:17,690 So let's find and find index.