1
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Great, we can increase the amount of items in a cart, so now let's start working with a decrease,

2
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let's bite the bullet and get it done.

3
00:00:09,560 --> 00:00:13,830
Now, the functionality will be almost exactly the same.

4
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However, we do need to check whether the amount is equal to one.

5
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So if the amount is equal to one, then we will remove the item from the cart.

6
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But initial set up will be exactly the same.

7
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Again, we are returning a new state so that let's copy the old state values for the time being will

8
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have a cost equal to our temporary variable.

9
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So I'm going to go with Unlet and stamp cardigan.

10
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And as far as the value for the time being, I'm going to set this equal to an empty array just because

11
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we are going to be checking if this is going to be undefined, we'll have another.

12
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So let me just overwrite this as a temp card then.

13
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Like I said, we have two options.

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Either the amount is equal to or bigger than one or it is in fact equal to one.

15
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And then, of course, we would want to remove that item.

16
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So I'm going to go with if action payload amount is equal to one, then do one thing.

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But then if the actual amount is not equal to one, which is going to be the case, of course, if the

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amount is bigger than one, then do something else and we will start with that, something else, because

19
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it's going to be a bit more easier because the actual functionality is exactly the same like we already

20
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have here.

21
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The only difference is that instead of increasing the amount, we will decrease.

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So if the amount is equal to one was just log, hey, it's one.

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And of course I cannot do this.

24
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I need to have my template literals.

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So let's write, hey, it's one.

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And then if it's not the case, then we're just going to decrease the amount.

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So like I said, we have our trump card at the moment.

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It is equal to an empty array, but we have already functionality for increasing and decreasing.

29
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It's exactly the same.

30
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Now let me copy and paste.

31
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And the only thing will change is, of course, we're not going to declare a new variable or variable

32
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will stay the same.

33
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So I'm going to go with timecard.

34
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And what I'm saying right now is, yes, at the moment it will be an empty array at the very beginning.

35
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But then if the amount is bigger than one and of course, we are going to assign it to a new array.

36
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Again, we're mapping over the items, were checking the ID if the matches and we just subtract one

37
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instead of add one.

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That's all.

39
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That's the only change we would need.

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Right.

41
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So let me save it.

42
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And then, of course, I'm going to be increasing.

43
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OK, fine.

44
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Awesome.

45
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And since that is bigger than one, each and every time I'm going to click, I will decrease that amount.

46
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So that is good.

47
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But of course, by the time I'm going to get the one, there should be a console.

48
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OK, so now it is equal to one.

49
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I click on it and now I just deleted the whole card.

50
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Why I deleted the cohort because time code is equal to an empty array.

51
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Correct.

52
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So we had in statement the value was equal to one.

53
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So we just cancel out page one and then instead of going for and else where we actually set our time

54
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card equal to an array with a decreased item, we just left it as an empty array.

55
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And that's why our card right now is empty.

56
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But we have our console log.

57
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Hey, it's one.

58
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So we successfully set up the functionality where we can decrease if the amount is bigger than one.

59
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Now let's fix up our code in our IF statement.

60
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So instead of simple console log, we will do a filter functionality again, just like we had before.

61
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So the same thing again, we just need to check if the amount is equal to one, then remove that item

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altogether.

63
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And again, this would be a case where it's much more simpler just to copy and paste.

64
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Now, I'm not a big fan of copying pasting the same time.

65
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Rewriting the same syntax just doesn't make sense.

66
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So let me copy everything from the state like.

67
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So let's scroll up where we have the amount, copy and paste.

68
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And then in this case, we are just going to set our timecard equal to state court.

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We filter out and then again, we're calling our callback function.

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We have our court remedy.

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So each and every item has the duty.

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And if the item does not match and as I can see here, I made some kind of bug because it should be

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action payload ID.

74
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Let me say it here and also probably, I should say, right here in the bottom as well, because something

75
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must have happened while I was working with my producer.

76
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So again, we just need to go back to action payload ID.

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That's the property that we're looking for.

78
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And now in this case, I can just check, OK?

79
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I can increase I can increase all of them, of course.

80
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And then the moment I'm going to go below one, you'll see how I remove the item again, which is decrease

81
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the amount.

82
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And then once we go below one, then we just remove the item from the cart.