WEBVTT 00:01.230 --> 00:07.800 OK, in previous lecture, you have seen how the store functions in variable, how to use function as 00:07.800 --> 00:11.130 a variable and also how to function as a parameter. 00:12.000 --> 00:17.640 The last thing that I want to show you regarding first class functions is how to return function from 00:17.640 --> 00:18.330 other function. 00:19.380 --> 00:19.830 All right. 00:20.190 --> 00:21.330 Let's go to Brackett's. 00:21.720 --> 00:28.290 And in order to demonstrate it, I'm going to use a little example again about exam scores and students. 00:28.860 --> 00:34.340 So using this example, I'm going to check if a student has passed an exam or failed. 00:34.680 --> 00:41.370 And also, according to student score, where he or she would start studying, I mean, start studying 00:41.370 --> 00:43.290 in university or in college. 00:43.860 --> 00:48.960 OK, at first I'm going to create the main function and call it the final result. 00:49.110 --> 00:51.510 So write function, final result. 00:54.010 --> 00:57.190 It will accept one parameter score. 00:59.420 --> 01:06.320 Then in order to define the range we need to use if our statement as a first condition, I'm going to 01:06.320 --> 01:16.160 define its core is greater than or equal to 81 points, if this condition is true, then students will 01:16.160 --> 01:18.040 start studying at university. 01:18.530 --> 01:22.490 I'm going to pass this result in function and then return that function. 01:22.940 --> 01:31.430 So rate return function, this anonymous function accepts one parameter, which will be the name of 01:31.430 --> 01:36.650 the student, the right name inside the parentheses, and then in Calabrese. 01:36.730 --> 01:36.980 Right. 01:36.980 --> 01:37.850 Cancel that log. 01:40.330 --> 01:41.380 Name plus. 01:43.860 --> 01:54.300 You passed an exam and you are a student of, let's say, state university. 01:58.070 --> 02:06.380 OK, after that, we need to define second case, I mean, if score is greater than or equal to 51, 02:07.040 --> 02:15.020 so we need to write else statement with the condition score is greater than or equal to 51. 02:18.420 --> 02:28.410 Then again, we need written statements, the right return function and pass here again, the parameter 02:28.830 --> 02:29.250 name. 02:31.440 --> 02:38.370 So if this condition is true, then suppose that the student will start studying in college, so. 02:38.370 --> 02:43.020 Right, cancel that log name plus. 02:45.190 --> 02:46.660 You passed an exam. 02:50.120 --> 02:53.060 And you are a student of. 02:55.070 --> 02:56.360 State College. 02:59.940 --> 03:07.500 OK, and the last part of the function is Elsah statement in which we will define if a student is failed, 03:07.890 --> 03:16.470 so right else then again return the function with parameter name. 03:20.100 --> 03:23.220 And inside the curly braces, White Castle, that log. 03:27.500 --> 03:30.410 Name plus, you failed. 03:34.040 --> 03:43.280 All right, everything is ready now it's time to call dysfunctions create a variable var, result one. 03:45.660 --> 03:54.150 Equals and right here, the name of the main function, final result with its arguments, let's say 03:54.450 --> 04:02.790 seventy seven points and then let's see in council what we will get right to consider log result one. 04:06.490 --> 04:14.050 Reload and he see that we had a function from else if statement, because this is core, I mean, seventy 04:14.050 --> 04:17.890 seven points is acceptable for the condition of else. 04:19.630 --> 04:26.140 As you see, as a result, we have function here from final result function and we just need to invoke 04:26.140 --> 04:27.610 it at first. 04:27.970 --> 04:41.410 Let's remove this constant log and write result one and pass the argument name as John reload. 04:42.550 --> 04:47.500 And we have John, you passed an exam and you are a student of state college. 04:48.760 --> 04:52.840 OK, let's see another case for other students. 04:52.840 --> 05:03.070 Let's say Jane, create again variable var result two equals and call the function again. 05:03.070 --> 05:16.900 Final result with the arguments in this case, write 44 points and then below write results to add the 05:16.900 --> 05:17.590 name Jane. 05:20.340 --> 05:27.870 Reload and we have Jane, you failed in this case, function from our statement was executed. 05:29.420 --> 05:38.780 All right, we can use a different type of syntax, it is like a shorthand method, we can write final 05:38.780 --> 05:49.010 results, the name of the main function with its argument right here, 96, and then open parentheses 05:49.940 --> 05:52.820 and write the name, for example, Mary. 05:55.660 --> 06:03.160 So it looks like kind of strange, but it works in this way as well, because JavaScript engine executes 06:03.160 --> 06:05.200 code from left to right. 06:05.740 --> 06:12.730 At first it executes final results function, then it reacts to second function and executes it with 06:12.730 --> 06:13.800 proper argument. 06:14.470 --> 06:15.460 So reload. 06:16.390 --> 06:20.890 And we have Mary, you pass an exam and your student of state university. 06:23.070 --> 06:27.270 All right, this was all about first class functions. 06:27.840 --> 06:29.010 See you in the next video.