1 00:00:03,440 --> 00:00:04,580 Welcome back. 2 00:00:04,610 --> 00:00:12,440 In this video, let's continue our array methods and we are going to talk about reduce method. 3 00:00:12,560 --> 00:00:12,950 Why? 4 00:00:12,950 --> 00:00:18,260 Before we explain, let's have a look at the data structure that we are going to work on. 5 00:00:18,950 --> 00:00:24,920 The first product is banana with price of $1, likewise orange, apple and pear. 6 00:00:24,950 --> 00:00:30,770 So what is reduced function where for this one to we have covered it before. 7 00:00:30,800 --> 00:00:33,380 So reduce function or method. 8 00:00:33,410 --> 00:00:41,240 It is used to compress an array into a single value, meaning we have reduced the entire array into 9 00:00:41,240 --> 00:00:42,470 a single value. 10 00:00:42,470 --> 00:00:46,520 So most cases we use reduce for calculations. 11 00:00:46,520 --> 00:00:54,410 So let's say that for this particular array, if I ask you that place, can you find me ordered to a 12 00:00:54,410 --> 00:00:57,920 top price for the product we have in store? 13 00:00:57,950 --> 00:01:02,090 Well, we can do that one by adding the prices together. 14 00:01:02,090 --> 00:01:02,750 Right. 15 00:01:02,750 --> 00:01:07,130 But assuming we have a bunch of products, how are we going to do. 16 00:01:07,160 --> 00:01:09,770 That's why reduce its shine. 17 00:01:10,340 --> 00:01:18,230 So let's see how you're going to use reduce you bring in our product as that and then we use method 18 00:01:18,260 --> 00:01:19,670 as a function call. 19 00:01:19,880 --> 00:01:23,180 So for this we this method is very special. 20 00:01:23,300 --> 00:01:29,330 All the methods takes in only one element as a callback buffer reduce. 21 00:01:29,360 --> 00:01:32,750 It says no, you need to give me two arguments. 22 00:01:32,780 --> 00:01:38,180 One is a callback function and then the nets are going to be the initialize, meaning where you want 23 00:01:38,180 --> 00:01:40,610 to start to add up the value together. 24 00:01:40,610 --> 00:01:41,780 So here we go. 25 00:01:41,810 --> 00:01:49,420 Let's use normal function here and I'll start a second argument comma and then what you are initialized 26 00:01:49,420 --> 00:01:49,650 to. 27 00:01:50,090 --> 00:01:54,380 So let's give it zero because you want to add up from zero, right? 28 00:01:54,530 --> 00:02:00,560 So inside this callback to we have access to three arguments that we can access. 29 00:02:00,560 --> 00:02:04,280 So here we can say accumulator or the current value. 30 00:02:04,280 --> 00:02:06,770 So let's say that for this one we have total. 31 00:02:06,800 --> 00:02:08,360 It can be anything here. 32 00:02:08,389 --> 00:02:12,870 The next one here are going to be the actual student in the list or products. 33 00:02:12,870 --> 00:02:15,230 Sorry, going to be the product itself. 34 00:02:15,410 --> 00:02:22,730 So here is going to be the individual product product. 35 00:02:22,940 --> 00:02:28,700 So inside my callback function here, let's try to console.log those values. 36 00:02:28,700 --> 00:02:36,410 The tutor first and let's save it, let's save it and let's see what we have as a tutor that zero meaning 37 00:02:36,410 --> 00:02:41,570 that by default we have zero because we begin at what zero. 38 00:02:41,570 --> 00:02:48,890 That's why we have four zero because for each loop we are not doing any logic but instead just console.log 39 00:02:48,890 --> 00:02:49,850 in total here. 40 00:02:49,850 --> 00:02:54,530 So now we know that the total represents our total value in our array. 41 00:02:54,620 --> 00:02:57,300 So what about let's check the product too. 42 00:02:57,350 --> 00:02:59,630 We're going to have the individual product here. 43 00:03:00,020 --> 00:03:08,120 So what we can do here is that first we are going to take the total here, which is zero, and then 44 00:03:08,120 --> 00:03:15,110 on each loop you want to add the zero to the price inside the array upon each loop. 45 00:03:15,110 --> 00:03:19,610 So first loop is going to add 0 to 2. 46 00:03:19,700 --> 00:03:24,890 Now the total has become two on a first loop, second loop is two. 47 00:03:24,890 --> 00:03:26,870 Then you're going to add 3 to 8. 48 00:03:26,870 --> 00:03:27,980 That is second loop. 49 00:03:27,980 --> 00:03:30,230 Now become five on third loop. 50 00:03:30,230 --> 00:03:35,390 We are going to add this one plus four, which gives us nine. 51 00:03:35,390 --> 00:03:38,330 So here we can return those values. 52 00:03:38,330 --> 00:03:44,750 We know that the total represents the zero here at the first loop or before the loop runs. 53 00:03:44,750 --> 00:03:46,490 So not going to be our tutor. 54 00:03:46,490 --> 00:03:49,880 And remember on the product is an object. 55 00:03:49,880 --> 00:03:52,940 So I want the price, only this price. 56 00:03:52,940 --> 00:03:57,170 So come here, I'm going to be the product dot price. 57 00:03:57,170 --> 00:04:03,860 So for this one is product p r for product. 58 00:04:04,430 --> 00:04:04,820 Yeah. 59 00:04:04,820 --> 00:04:07,280 So this one here like that. 60 00:04:07,280 --> 00:04:15,830 So for this one, we can assign to a variable and say sum of products or is it price. 61 00:04:15,830 --> 00:04:21,019 It can be price or product, some product price or key product. 62 00:04:21,110 --> 00:04:22,370 This is some price. 63 00:04:22,400 --> 00:04:23,820 This is some whatever. 64 00:04:24,110 --> 00:04:24,530 Yeah. 65 00:04:24,530 --> 00:04:30,500 So here if I cancel look sum or total, we're going to see that we have ten.