WEBVTT 00:01.370 --> 00:05.300 The next that I want to introduce you are filter and fight. 00:05.970 --> 00:11.330 I decided to describe both of them in one video because they work in similar and simple way. 00:11.690 --> 00:14.660 So I don't want to consider them separately. 00:15.020 --> 00:15.530 All right. 00:16.040 --> 00:17.790 Let's write some examples. 00:17.810 --> 00:20.000 I'm going to start with the filter holper. 00:20.240 --> 00:26.480 For that, I want to create an array of persons which will consist of several objects and suppose that 00:26.480 --> 00:29.240 we want to filter these objects depending on some condition. 00:30.130 --> 00:33.250 So that's right, verbal person's. 00:34.750 --> 00:46.750 That insert here an object with property name Mary and then right, another property, gender female, 00:48.230 --> 00:53.010 let's duplicate it three more times and change names and genders properly. 00:53.020 --> 00:54.840 Right, John? 00:55.720 --> 00:59.620 And gender male, then, Jane. 01:02.830 --> 01:12.520 That Bob and gender male, OK, as we said, we want to filter those objects and suppose that we want 01:12.520 --> 01:17.400 to choose only male objects and add them into a new era for that. 01:17.410 --> 01:19.540 At first, we need to create a new area. 01:20.350 --> 01:21.720 Let's call it males. 01:22.750 --> 01:28.210 Then we need to use for a loop in order to iterate through the items, choose the proper one and using 01:28.210 --> 01:34.780 push method, add it to new right, create for a loop by its variable equal to zero. 01:35.440 --> 01:39.340 Then the condition is less than the length of a person's. 01:40.440 --> 01:41.610 Then I plus plus. 01:43.360 --> 01:49.180 Here, we're going to use your statement and as a condition, we need to check if gender of the person 01:49.180 --> 01:53.230 is equal to male rights if persons. 01:54.630 --> 02:00.270 I doubt gender equals to male. 02:03.200 --> 02:08.660 So if this condition is true, then we need to write mail, start, push. 02:10.550 --> 02:14.390 And as a parameter persons' I. 02:17.220 --> 02:21.330 So let's lock them in council writes the blog Persons'. 02:23.810 --> 02:25.940 And then cancel the log mails. 02:29.010 --> 02:36.240 Reload and here we have at first original persons are right, and then the filtered one, which consists 02:36.240 --> 02:37.320 of male persons. 02:38.460 --> 02:44.060 All right, this is the way which uses follow up, and I'm going to do the same using Filter Harper, 02:44.490 --> 02:47.730 but before that, let's again separate the codes. 02:51.100 --> 02:57.790 I'm going to create variable females, add in this variable, I'm going to store this case female persons, 02:58.210 --> 03:02.530 so create variable females, which equals two persons. 03:03.780 --> 03:09.340 Use your filter helper, the syntax again is similar as it was in case of previous helpers. 03:09.840 --> 03:14.850 We need to pass your anonymous function with the parameter person, which again will be in singular 03:14.850 --> 03:15.180 form. 03:17.460 --> 03:22.710 So, as we said, we want to choose female persons, therefore we need to write a written statement 03:23.040 --> 03:30.510 in which the gender property should be equal to female white return person, not gender. 03:32.320 --> 03:33.940 Two people equals two female. 03:36.700 --> 03:41.470 Let's again look both variables in council, right, castle log persons. 03:44.380 --> 03:46.570 And that costs a lot of females. 03:49.950 --> 03:56.100 Reload and you see that at first we have, again, original persons are right and then filtered Arah, 03:56.100 --> 03:58.440 which consists of female persons. 03:59.400 --> 04:02.640 So Filter Method did absolutely the same job as follow. 04:02.660 --> 04:09.000 But again, you see at a glance that we needed for that less time because of less amount of code. 04:09.240 --> 04:14.130 And again, logic is very simple and easy to understand in case of filter hopper. 04:14.970 --> 04:19.710 All right, let's take a look in depth how filter hopper actually works behind the scenes. 04:20.160 --> 04:23.520 So here we have our persons array with it's containing objects. 04:24.150 --> 04:28.290 Then we have the variable females in which female persons should be added. 04:28.740 --> 04:35.880 And also here we have a filter hopper on first iteration function is executed for the first object with 04:35.880 --> 04:36.930 no property marry. 04:37.560 --> 04:39.830 Because of that, Mary has the gender female. 04:39.870 --> 04:41.900 The condition inside function is true. 04:42.360 --> 04:46.020 Therefore it returns to value and the object is added to female Arite. 04:46.980 --> 04:53.850 The function is executed for the second object, which has name property John and the gender male condition 04:53.850 --> 04:54.460 is false. 04:54.930 --> 04:59.160 So function returns false value and therefore object is not added to a right. 05:00.120 --> 05:03.810 Then in the same way function is executed for the object. 05:03.810 --> 05:05.850 Jane condition is through. 05:05.850 --> 05:07.430 An object is added to a right. 05:08.160 --> 05:14.910 As for the object, you see that gender is male function, which false value because condition is false. 05:15.310 --> 05:17.460 Therefore object is not added to the right. 05:18.690 --> 05:19.140 All right. 05:19.530 --> 05:22.080 That's the way our filter Hartill actually works. 05:22.810 --> 05:28.710 Let's go to Brackett's and move on to the next helper, which is find, as we said, find works in the 05:28.710 --> 05:30.660 similar way as filter householder's. 05:31.140 --> 05:32.940 But there is only one difference. 05:33.480 --> 05:41.160 Filter Holper iterate through of the items in array and adds enumerate the item for which the condition 05:41.160 --> 05:41.580 is true. 05:42.120 --> 05:48.840 But in case of found helper, when it finds that condition is true, it adds this current item in new 05:48.840 --> 05:51.740 array and immediately terminates iteration. 05:52.980 --> 05:53.670 Makes sense. 05:54.800 --> 06:03.320 OK, so if we change here, filter into find and then reload, we'll will get onto the first object 06:03.320 --> 06:07.070 because the condition for the first item is through and find out how it stops. 06:07.070 --> 06:12.020 Iteration, we can reach the same result if we use followup for that. 06:12.020 --> 06:17.570 We just need to pass your known break statement, which actually stops looping through the items. 06:17.840 --> 06:18.340 So right. 06:18.350 --> 06:21.170 Break, then reload. 06:21.740 --> 06:23.560 And you see that we have the same result. 06:24.650 --> 06:28.250 OK, let's consider briefly how found Harper works. 06:29.060 --> 06:37.340 Again, we have here our person story that the females variable and find helper, so are the first iteration 06:37.340 --> 06:43.670 function is executed for the first item, which is an object within the property and gender female. 06:44.270 --> 06:46.130 The condition inside function is true. 06:46.730 --> 06:47.630 It returns true. 06:47.630 --> 06:54.020 Value object is added to females array and after that helper terminates working. 06:55.570 --> 06:59.080 So this is the way I'll find help actually works behind the scenes. 07:00.280 --> 07:01.960 All right, that's it. 07:02.200 --> 07:03.450 See you in the next lecture.