WEBVTT 00:00.240 --> 00:06.300 It's time to refer to another very important aspect in JavaScript, which is called functions, because 00:06.300 --> 00:10.400 of that, this section is about from basic to intermediate JavaScript. 00:10.890 --> 00:14.190 We will discuss what the functions just are and how they work. 00:14.880 --> 00:18.830 But in coming sections, you will see how they act in advanced JavaScript. 00:19.950 --> 00:24.250 Sometimes you may need to write some code and then repeat this code over and over again. 00:24.720 --> 00:26.880 This is the case when we use functions. 00:28.680 --> 00:34.240 They allow us to minimize the amount of our code and they are very flexible to use. 00:34.800 --> 00:36.720 Let's see what the functions really are. 00:37.410 --> 00:43.000 Functions like a group, a series of statements together to perform a specific task. 00:43.740 --> 00:50.730 So as we said, if different parts of a script repeat the same task, you can reuse the function rather 00:50.730 --> 00:52.920 than repeat the same set of statements. 00:54.200 --> 01:01.340 All right, in order to create a function, we need to write a keyword function followed by the function 01:01.340 --> 01:01.680 name. 01:02.990 --> 01:06.260 That name should describe the task function is performing. 01:07.370 --> 01:12.410 Then we have to place parentheses in which we can pass parameters. 01:13.670 --> 01:19.900 We use parameters when functions need to be provided with information in order to achieve a given task. 01:19.940 --> 01:25.340 The steps that the function is to do in order to perform this task are written in a code block. 01:25.550 --> 01:32.000 Inside the process, the code block consists of one or more statements and you do not write the semicolon 01:32.420 --> 01:36.740 after the closing calibrates like you do it after the usual statements. 01:38.200 --> 01:43.180 All right, let's write something inside the code blog, the blog. 01:44.160 --> 01:44.970 Hello, world. 01:48.250 --> 01:51.480 Reload the page and see that we have nothing. 01:51.520 --> 01:56.530 You so the statements in the function are not always executed when the page loads. 01:57.220 --> 02:02.030 In order to do that, you need to call or in other words, invoke the function. 02:02.860 --> 02:07.750 It's very simple to do it just need to write function name with parentheses. 02:09.530 --> 02:11.100 So we've got here. 02:11.150 --> 02:17.450 Hello, World in Council, all right now, right, a bit more complex example. 02:17.690 --> 02:23.780 Suppose that person is passing an exam and trying to enroll in university or at least in college. 02:24.530 --> 02:26.740 For that, the person needs to get the proper score. 02:27.200 --> 02:31.140 So write the function and call it pass exam. 02:32.810 --> 02:38.270 I'm going to use your two parameters, name of the student and score. 02:39.260 --> 02:46.000 Then imagine that in order to passing university, it's required to get at least 71 points. 02:46.670 --> 02:57.800 So create a new variable, call it plus unique and assign to devalue seven to one and after that create 02:57.800 --> 03:01.970 another variable which will be lower limit for passing an exam in college. 03:02.420 --> 03:02.830 Right. 03:02.840 --> 03:06.560 Verbal pass call equals to 51. 03:07.240 --> 03:10.660 OK, now we are going to use each statement. 03:10.700 --> 03:13.400 We are already familiar with that at first. 03:13.400 --> 03:16.900 Let's check if the person could enroll in university. 03:17.420 --> 03:18.080 So right. 03:18.080 --> 03:26.720 If score is greater than or equal to pass uni, then run in Castle. 03:29.180 --> 03:37.340 Place your name Parameter Plus has enrolled in university with. 03:38.970 --> 03:39.420 And. 03:40.510 --> 03:41.730 Here, we need more. 03:43.080 --> 03:44.430 Then plus points. 03:47.140 --> 03:53.530 So if this condition is false, which means that he or she has got lower than the limit in university 03:53.530 --> 04:00.190 was required, then we need to use elective statements which will check if a person could enroll in 04:00.190 --> 04:00.690 college. 04:01.450 --> 04:02.170 So right. 04:02.190 --> 04:02.860 Else if. 04:04.000 --> 04:08.950 And the condition score is greater than or equal to Pascal. 04:11.850 --> 04:15.630 Then inside the Brace's right Coslett log. 04:18.940 --> 04:23.560 Then copy it from if statement and just change. 04:26.040 --> 04:31.320 University into college and the next possible case is to fail. 04:31.830 --> 04:34.200 For that, let's use our statement. 04:35.830 --> 04:37.180 And then running castle. 04:38.400 --> 04:41.640 Name plus has failed. 04:44.700 --> 04:51.060 All right, function is ready, but as we said, in order to execute all those codes, we need to call 04:51.060 --> 04:51.930 it so. 04:51.930 --> 04:54.460 Right, the name of the function pass exam. 04:55.720 --> 05:05.020 And pursue the relevant arguments, right, John, as the name of the student and score 75. 05:06.710 --> 05:16.280 Reload the page and you see that we have here, John, has enrolled in university with 75 points, that's 05:16.280 --> 05:19.360 the power of functions for every next student. 05:19.370 --> 05:21.230 You don't need to write this code again. 05:21.590 --> 05:26.710 You just need to call this function over and over again and just change the arguments. 05:27.560 --> 05:29.170 So let's do it right. 05:29.180 --> 05:38.270 Pass exam, then place your as the name Mary and as score 65. 05:40.520 --> 05:45.230 Then to the same again and pursue your arguments as Bob. 05:46.420 --> 05:48.070 And that 45. 05:49.990 --> 05:53.000 Reload and we have the proper results. 05:53.620 --> 05:56.860 John has enrolled in university with seven to five points. 05:57.430 --> 06:03.140 Mary has enrolled in college with 65 points, and Bob has failed. 06:04.330 --> 06:04.870 All right. 06:05.540 --> 06:09.450 You may notice that sometimes I set parameters and arguments. 06:10.240 --> 06:15.000 So let me explain what is the difference between them, what the function was declared. 06:15.010 --> 06:21.150 You saw the words name and score used these words acting the same way as variables. 06:21.700 --> 06:24.280 So they are called parameters. 06:24.880 --> 06:32.230 But what the function was called, we specified real names and actual scores of the students that were 06:32.260 --> 06:33.510 used to get the results. 06:33.970 --> 06:36.430 These values are called arguments. 06:37.890 --> 06:38.540 Makes sense. 06:40.470 --> 06:42.690 So those are parameters. 06:43.930 --> 06:46.120 And those are arguments. 06:47.620 --> 06:57.640 All right, suppose that core consists of quiz score and s.A score points, we can create a function 06:57.640 --> 06:59.670 which will calculate the total score. 07:00.660 --> 07:11.970 Right, function and call it calculates court that insert here two parameters for Questcor and for s.A 07:11.970 --> 07:12.420 score. 07:15.100 --> 07:22.330 Then inside codebook create a variable score, which equals to Questcor, plus a set score. 07:26.700 --> 07:31.950 So in order to get this core value, we need to use special keyword return. 07:33.050 --> 07:39.620 The return statement stops the execution of a function and returns the value from that function. 07:40.680 --> 07:47.490 In this case, we want to get a core value, therefore we have to right return its core. 07:49.170 --> 07:56.250 Now, let's call this function as the arguments inside the past example function and set the arguments 07:56.250 --> 08:03.990 for that function, for example, as forty four Questcor and 34 essay's court. 08:04.410 --> 08:09.300 So this function will calculate core value and return it as an argument. 08:09.300 --> 08:14.100 For example, function, reload the page and see. 08:14.460 --> 08:17.850 John has enrolled in college with 70 points. 08:18.860 --> 08:24.230 Seventh is the sum of 30 and 40, which are the arguments of recalculates court function. 08:25.780 --> 08:26.440 Makes sense. 08:27.880 --> 08:34.690 OK, so in this lecture, we have discussed what the functions are in JavaScript, how they work and 08:35.080 --> 08:37.900 what are they use for that's what.