WEBVTT 00:01.380 --> 00:04.240 Let's move on to the next hour, helpers, in this lecture. 00:04.260 --> 00:07.010 I want to introduce you every and some helpers. 00:07.470 --> 00:12.980 I decided to demonstrate those helpers in one video because they work in a similar way as it was in 00:12.990 --> 00:14.790 case of filter and find helpers. 00:16.070 --> 00:22.190 As usual, before we consider how those helpers actually work, I'm going to use follow up in order 00:22.190 --> 00:27.290 to compare it to them and also demonstrate how convenient and faster approaches they are. 00:27.860 --> 00:36.410 For that, I'm going to create a right of persons in which I will insert some objects with properties, 00:36.410 --> 00:37.410 name and age. 00:38.330 --> 00:47.570 So right here, John and the age 28, let's duplicate it three times and also change the values, right, 00:48.020 --> 00:48.620 Mary? 00:50.400 --> 00:55.140 Than the age 20 then, right, Nick? 00:56.830 --> 00:57.850 And 15. 00:59.760 --> 01:04.290 And then finally, right, Jane, and the age 40. 01:06.270 --> 01:14.370 OK, so here we have persons with names and ages and we wonder if all of those persons or only some 01:14.370 --> 01:15.980 of them can vote in elections. 01:16.930 --> 01:22.360 And we're going to figure out in it according to their ages, for that, first of all, we will use 01:22.360 --> 01:25.960 follow up, but before that, I'm going to create variables. 01:26.900 --> 01:31.370 Let's call it every person can vote. 01:33.540 --> 01:37.290 As I default, let's assign to this variable through value. 01:38.750 --> 01:43.220 That creates another one and call it only some. 01:44.190 --> 01:45.960 Persons can vote. 01:47.780 --> 01:52.100 And in this case, as I default, let's assign to this variable false value. 01:53.380 --> 01:55.720 All right, now let's use follow up. 01:56.710 --> 01:58.660 Right, well, equal to zero. 01:59.920 --> 02:03.730 Then compare it to the length of a person's. 02:06.240 --> 02:07.560 And then I plus plus. 02:11.220 --> 02:18.540 So if one of those persons age is less than 18, then we want to change the value of every person can 02:18.540 --> 02:21.420 vote variable from true into force. 02:22.320 --> 02:27.810 And in the same way, we want to change the value of only some persons can vote variable from force 02:27.810 --> 02:28.500 into two. 02:29.520 --> 02:34.760 For that info, we need to create if statements which should have the following condition. 02:35.990 --> 02:39.260 If persons I dot h. 02:41.510 --> 02:42.800 Is less than 18. 02:44.450 --> 02:52.430 So if this condition is true, if one of the person's age is less than 18, then we need every person 02:52.880 --> 02:55.880 can vote equal to false. 02:57.590 --> 03:02.720 And at the same time, we need to assign to some persons can vote variable. 03:03.770 --> 03:04.760 Disvalue, true. 03:05.390 --> 03:07.850 All right, let's Log-in Council. 03:09.090 --> 03:13.260 Right here, every person can vote. 03:16.120 --> 03:17.290 Then the Desh. 03:18.230 --> 03:21.830 And place you every person can vote variable. 03:24.140 --> 03:26.360 And then again, running council. 03:28.570 --> 03:31.510 Only some persons can vote. 03:34.660 --> 03:35.200 Plus. 03:37.160 --> 03:39.230 The variable, only some persons can vote. 03:41.010 --> 03:48.150 All right, let's reload and see that every person can vote is false and only some persons can vote 03:48.150 --> 03:48.630 is true. 03:49.320 --> 03:56.730 Actually it's obvious because in person we have Nick, which is 15 years old, if we change it and writes, 03:56.730 --> 03:58.170 for example, 25. 03:59.780 --> 04:06.080 Then we will get the opposite values every person can vote is true, and only some persons can vote 04:06.080 --> 04:06.580 is false. 04:07.720 --> 04:14.710 OK, so using follow, we have figured out if every person from Iraq can vote or only some of them can 04:14.710 --> 04:16.870 vote, it's nice, it works. 04:16.870 --> 04:22.360 But as you notice for that, we have used a bit more logic and so much coding. 04:23.050 --> 04:27.800 Instead of this stuff, we are able to use every helper methods, every and some. 04:28.660 --> 04:35.110 At first, let's use every helper, which gives us boolean value true or false ID checks condition four 04:35.110 --> 04:36.040 of the items. 04:36.730 --> 04:40.290 And if the condition is true for all of them, it returns true. 04:40.810 --> 04:46.640 But if the condition is false, at least for one item, then it returns false. 04:47.530 --> 04:50.650 So create variable and call it every. 04:52.360 --> 04:58.600 Then assigned to it persons and yes, your every hour I help her with. 04:59.560 --> 05:05.390 And anonymous function and then insert here as a parameter person. 05:08.450 --> 05:12.200 Then, as you remember, we need written statements. 05:14.110 --> 05:19.930 Because of that, we wonder if a person can vote or not win at the following condition person, that 05:19.930 --> 05:24.430 age is greater than or equal to 18. 05:25.890 --> 05:28.080 Let's log in Castle to variable every. 05:31.610 --> 05:37.890 Then reload the page, and we have true because all persons ages are greater than 18. 05:38.570 --> 05:46.220 If we change one of them and writes, for example, for merry age 10, then we will get false. 05:47.480 --> 05:51.230 All right, let's consider in depth how every helper works. 05:51.800 --> 05:54.590 So here we have a person's array with objects. 05:55.550 --> 06:01.910 And also, every helper, whether it's a right to function on the first iteration function, is executed 06:01.910 --> 06:05.750 for first item John, his age is 28. 06:06.200 --> 06:10.940 Therefore, condition is true and every helper returns true value after first iteration. 06:11.970 --> 06:16.300 On the second iteration, function is executed for second object, Mary. 06:17.040 --> 06:19.980 The condition is still true because her age is 20. 06:20.580 --> 06:28.920 Every helper again returns true after that function is executed for third object, Nick, his age is 06:28.920 --> 06:29.430 15. 06:30.120 --> 06:32.730 So condition is false and we get false value. 06:33.960 --> 06:40.140 As soon as we get full value, every help or terminates situation and we get final value as false. 06:41.490 --> 06:48.060 You can imagine that every Harper uses logical and operator and you know that in case of an operator, 06:48.420 --> 06:51.770 if all conditions are true, we get through finally. 06:52.380 --> 06:57.080 But if at least one of the conditions is false, then we get false value. 06:57.900 --> 07:00.620 The exact same happens in case of every holper. 07:01.680 --> 07:08.250 Also, remember that as soon as every helper finds false value, it immediately terminates iteration 07:08.940 --> 07:12.260 because continuing execution of function won't make any sense. 07:13.220 --> 07:17.960 It's nice feature because it helps JavaScript engine to execute code faster. 07:18.890 --> 07:24.830 All right, let's go back to Brackett's and as usual, let's prove what I have just said for that. 07:24.830 --> 07:31.700 At first, I'm going to create variable X and assign to its value as zero. 07:33.150 --> 07:35.470 This variable actually will be counter. 07:35.880 --> 07:38.300 I want to show you what happens on each iteration. 07:39.000 --> 07:40.470 Let's run in council. 07:41.750 --> 07:50.390 Right here, plus plus X, I wrote plus plus increment operator before the variable X in order to get 07:50.390 --> 07:52.400 directly one instead of zero. 07:52.820 --> 07:57.110 If I wrote it after X, then we would get zero at first. 07:58.220 --> 08:06.070 Then, right, plus dash and then plus the condition person dot h. 08:07.670 --> 08:11.380 Is greater than or equal to 18. 08:13.030 --> 08:16.990 And also for Mary, changed back into 20. 08:18.990 --> 08:21.000 All right, reload the page. 08:22.020 --> 08:25.120 So you see, on every situation, condition is true. 08:25.590 --> 08:32.310 That's why we have four iterations and also that's the reason why we have true value as a result if 08:32.310 --> 08:34.800 we change the age of marriage into 10. 08:37.170 --> 08:44.370 Then we will get on first iteration through value, add on second one, false also you see that third 08:44.370 --> 08:46.890 and fourth iterations are not executed anymore. 08:47.220 --> 08:51.570 And because of the false value on second iteration, finally we have false. 08:53.320 --> 08:57.530 All right, I think that regarding every Harpur, everything is clear for you. 08:58.300 --> 09:00.600 Let's go ahead and talk about some helper. 09:01.420 --> 09:09.400 So here we have a right of persons, but in this case with different ages, also here we have some helper. 09:10.560 --> 09:17.880 On the first iteration, function is executed for first object, John, his age is 10, therefore condition 09:17.880 --> 09:20.400 is false and somehow operates on false value. 09:21.330 --> 09:24.010 Unlike every helper, it continues and moves on. 09:24.040 --> 09:27.930 Second, iteration function is executed for second object. 09:27.930 --> 09:33.120 Memory condition is still false and again, somehow Puritan's false value. 09:34.130 --> 09:40.580 Then function is executed for third object, Nick, in this case, condition is true because his age 09:40.580 --> 09:44.840 is greater than 18 and somehow Puritan's true value. 09:45.890 --> 09:52.500 As soon as it finds true value, it terminates iterations and gives us, as a result, value. 09:52.560 --> 09:58.730 True, I like every helper some uses logical or operator. 09:59.760 --> 10:02.590 So, again, somehow project's condition. 10:03.030 --> 10:10.920 And as soon as it finds true value stops iterations, but if condition is false for all items, then 10:10.920 --> 10:14.130 this is the only case when somehow Harpur returns false value. 10:15.450 --> 10:16.110 Makes sense. 10:17.010 --> 10:22.830 All right, let's go back to Brackett's and change everything into some. 10:24.140 --> 10:26.510 Also, change the condition and write. 10:29.580 --> 10:32.640 Person, that age is less than or equal to 18. 10:34.360 --> 10:42.220 Revote and we got on first iteration false value add on second iteration, we have to do so on second 10:42.220 --> 10:47.530 iteration somehow found true value and as a result it returns true. 10:48.340 --> 10:55.990 If we change the age of marry and write 20, then we will get false in all four iterations and for a 10:55.990 --> 10:57.150 final result as well. 10:58.980 --> 10:59.460 All right. 11:00.570 --> 11:04.500 It was all about average and some helpers see you in the next video.