1 00:00:00,740 --> 00:00:01,910 In this video. 2 00:00:01,940 --> 00:00:04,280 Let's talk about find. 3 00:00:06,700 --> 00:00:06,870 Okay. 4 00:00:07,000 --> 00:00:11,290 So let me comment this one out and then comment out these ones. 5 00:00:11,500 --> 00:00:19,360 So find is also one of the array methods that we often use most at times. 6 00:00:19,840 --> 00:00:22,900 So let's see what does find mean? 7 00:00:22,900 --> 00:00:31,240 If you get back to MongoDB, you understand what find is about MongoDB find is in contrast with find 8 00:00:31,240 --> 00:00:32,470 in JavaScript. 9 00:00:32,470 --> 00:00:34,690 So let's see what find means. 10 00:00:34,690 --> 00:00:41,020 Well, as the name implies, it is used to find element in an array list. 11 00:00:41,020 --> 00:00:42,010 I want to find. 12 00:00:42,010 --> 00:00:47,200 For the meantime let's declare variable cons as edges. 13 00:00:47,290 --> 00:00:53,890 Edges array is equal to we have ten years, ten years. 14 00:00:53,890 --> 00:00:55,630 We have 20 years. 15 00:00:55,810 --> 00:00:59,590 We have 30 years, we have 50 years. 16 00:00:59,590 --> 00:01:03,370 And we have let's say, I mean 24 years. 17 00:01:03,880 --> 00:01:04,480 Okay. 18 00:01:04,690 --> 00:01:16,870 So here we can I can ask you that place in this array, find me all the edges that is less than 20 years 19 00:01:16,870 --> 00:01:17,980 in this array. 20 00:01:18,220 --> 00:01:18,730 Right? 21 00:01:18,730 --> 00:01:29,110 So I'm going to use fine to make this happen, but find also execute a function for every array element. 22 00:01:29,590 --> 00:01:38,890 So it's always retained undefined if there is no matching element in your search criteria or in your 23 00:01:38,890 --> 00:01:39,490 logic. 24 00:01:39,880 --> 00:01:44,920 And one more time the fine method does not mutate the original array. 25 00:01:45,100 --> 00:01:46,030 So let's see. 26 00:01:46,810 --> 00:01:53,800 So let's say that for this I want to find all edges less than 20. 27 00:01:53,980 --> 00:01:54,880 So here we go. 28 00:01:55,000 --> 00:02:03,370 The same process for I mean, for reduce the same syntax for the meantime, let's also write the syntax 29 00:02:03,370 --> 00:02:12,430 here, the array dot find and as a function here, the same process you pass in a callback function 30 00:02:13,150 --> 00:02:13,840 as that. 31 00:02:13,840 --> 00:02:17,380 But for this one it takes only one element online. 32 00:02:17,380 --> 00:02:21,280 They reduce, they pass in another argument. 33 00:02:21,310 --> 00:02:30,460 So here for this one, we have the actual I mean, data that can make as data or record. 34 00:02:30,460 --> 00:02:36,790 So this what I find here represent the individual data inside the array. 35 00:02:36,790 --> 00:02:41,170 So this one represents the individual records in this particular array. 36 00:02:41,830 --> 00:02:43,540 So here and that is it. 37 00:02:43,540 --> 00:02:48,160 Then you can make your logic routine, whether it is more than $2 and four. 38 00:02:48,610 --> 00:02:49,930 So here you go. 39 00:02:50,110 --> 00:02:51,670 So this is a syntax. 40 00:02:52,890 --> 00:02:54,000 Sin. 41 00:02:56,260 --> 00:02:56,920 Tax. 42 00:02:57,070 --> 00:02:57,790 Perfect. 43 00:02:57,790 --> 00:02:58,870 So now let's see. 44 00:02:58,870 --> 00:03:01,960 So let's say that find. 45 00:03:03,620 --> 00:03:04,400 H. 46 00:03:06,810 --> 00:03:08,400 Less than. 47 00:03:09,700 --> 00:03:10,630 Hmm. 48 00:03:10,660 --> 00:03:12,940 Three years in this area. 49 00:03:12,970 --> 00:03:14,680 How are you going to do it? 50 00:03:15,130 --> 00:03:16,270 So the same process. 51 00:03:16,270 --> 00:03:26,080 I would take my ages array to find and then find as a function pass in my callback function parentheses 52 00:03:26,080 --> 00:03:27,520 and my carry braces. 53 00:03:27,790 --> 00:03:28,630 Here we go. 54 00:03:29,020 --> 00:03:32,860 So here we have access to the individual record in this array. 55 00:03:32,890 --> 00:03:35,560 Then I can represent this one with a variable. 56 00:03:35,590 --> 00:03:37,630 It can be any. 57 00:03:37,660 --> 00:03:40,210 It can be whatever. 58 00:03:40,240 --> 00:03:42,430 It can be foo. 59 00:03:42,940 --> 00:03:43,630 Those. 60 00:03:43,630 --> 00:03:48,430 This one represent the actual data in the. 61 00:03:49,740 --> 00:03:51,710 The individual data in the array. 62 00:03:51,720 --> 00:03:58,210 So if I cancel that log foo see that I get them here. 63 00:03:58,710 --> 00:04:04,640 First one is ten, 20, 30, 50 and 24. 64 00:04:04,650 --> 00:04:16,320 So now when I get it back I can nine return and see that well find it is less than 30 so you can see 65 00:04:16,320 --> 00:04:20,579 that fus let me see h h here. 66 00:04:20,760 --> 00:04:22,740 So I would say h. 67 00:04:23,690 --> 00:04:25,820 Less than 30. 68 00:04:26,690 --> 00:04:27,650 Do we have some? 69 00:04:28,010 --> 00:04:31,100 So we do have some record that are less than 30. 70 00:04:31,130 --> 00:04:34,000 Yes, we have 20 and 30. 71 00:04:34,010 --> 00:04:36,140 So let's see if I'm going to get this one. 72 00:04:36,140 --> 00:04:41,330 But this record data are not less than what I mean 30. 73 00:04:41,360 --> 00:04:46,250 So it will not display this. 74 00:04:46,250 --> 00:04:48,230 So let's assign the results. 75 00:04:49,820 --> 00:04:54,140 So a cost, let's say, result equal to that. 76 00:04:54,560 --> 00:04:59,240 So down here, let's consider that look the result. 77 00:05:01,720 --> 00:05:02,250 Okay. 78 00:05:02,530 --> 00:05:03,240 You see that? 79 00:05:03,250 --> 00:05:05,020 I get ten. 80 00:05:05,990 --> 00:05:13,220 Guys, you see some weird things here, even though I have 20 here, but it's not retained that. 81 00:05:14,070 --> 00:05:17,160 If I remove ten, let's see. 82 00:05:17,340 --> 00:05:18,510 I get 20. 83 00:05:19,690 --> 00:05:30,430 So the takeaway here is that find retain a single value that matches our criteria. 84 00:05:31,310 --> 00:05:40,160 Again find retains a single value or the first matching value based on our criteria. 85 00:05:40,730 --> 00:05:45,710 And our criteria here is, is that the age must be less than 30. 86 00:05:46,010 --> 00:05:50,930 So if I bring let's save in two years here is going to return what? 87 00:05:50,930 --> 00:05:53,870 And I bring five here and then six year. 88 00:05:54,080 --> 00:06:01,670 All these ages are less than 30, but it's going to return the first one that matches because this one 89 00:06:01,870 --> 00:06:08,420 when looking through as soon as he saw this one and it matches our logic here, logic here is going 90 00:06:08,420 --> 00:06:09,230 to return it. 91 00:06:09,470 --> 00:06:18,650 So if I save this one, I see two that is going to bear in mind about find the next video. 92 00:06:19,100 --> 00:06:22,370 Let's say that we want to find all matching criteria. 93 00:06:22,400 --> 00:06:24,380 How are we going to do it? 94 00:06:24,560 --> 00:06:28,160 That's why we talk about another method called filter.