WEBVTT 00:01.500 --> 00:06.870 Now it's time to consider another very helpful and convenient feature which was released in Essex, 00:07.260 --> 00:09.480 I'm going to talk about default parameters. 00:10.230 --> 00:13.140 Let's go to Brackett's and create function. 00:14.580 --> 00:15.870 Let's call that person. 00:17.700 --> 00:26.520 And insert here three parameters, first name, last name and profession. 00:28.880 --> 00:30.230 Then running council. 00:33.570 --> 00:37.290 Right, I am right, first name. 00:39.090 --> 00:48.810 Then last name, then the text, and I am and place your thought parameter profession. 00:51.460 --> 00:59.730 Then invoke this function and as an argument, let's place here on the first name, for example, John, 01:00.400 --> 01:05.440 so as you see, function has three parameters, but as arguments, we have only one. 01:06.340 --> 01:09.570 If we reload, we will get I am John. 01:10.120 --> 01:13.290 But as for a last name and profession we have here undefined. 01:14.290 --> 01:17.320 The reason is that we did not insert the rest of the arguments. 01:17.890 --> 01:24.550 JavaScript engine found here one argument and as a default, it has been represented as the first parameter 01:24.700 --> 01:25.330 first name. 01:25.540 --> 01:29.130 In order to fix that in ESPIED, we have several ways. 01:29.800 --> 01:36.550 First one is to use a statement and as a condition we have to place your last name. 01:37.120 --> 01:40.350 Three equals to undefined. 01:40.690 --> 01:45.910 So if this condition is true, we need to assign the value to last name parameter. 01:46.870 --> 01:48.280 For example, as Smith. 01:50.920 --> 01:56.860 The exact same thing we have to do for third parameter, which is profession, so creative statement 01:57.640 --> 02:03.340 as a condition, right profession to people equals to undefined. 02:05.800 --> 02:09.010 So, again, if this condition is true, then we need to right. 02:09.010 --> 02:14.410 Profession equals to, let's say, programer. 02:15.410 --> 02:19.850 So if we reload the page, we will get the results, what we wanted. 02:20.390 --> 02:22.990 I'm John Smith and I am programer. 02:23.270 --> 02:27.290 OK, now let's insert second and third arguments and rights. 02:27.290 --> 02:36.290 For example, though, as last name and then instructor as profession. 02:36.980 --> 02:38.000 Reload the page. 02:38.630 --> 02:41.600 And we have I'm John Doe and I am an instructor. 02:42.260 --> 02:45.460 In this case, the conditions in if statements were false. 02:46.160 --> 02:51.620 So the code inside them was executed and we got the result with a different last name and profession. 02:52.100 --> 02:54.380 So this is one way to fix that problem. 02:54.380 --> 03:02.180 But besides that, instead of if statements we can use logical or operator and achieve the same results, 03:03.290 --> 03:08.870 let's do it for professional parameter delete if statement and instead of it. 03:08.870 --> 03:16.220 Right profession equals to profession or programmer. 03:18.890 --> 03:25.690 This is kind of short wait and using your statement, so when we invoke function, if we insert their 03:25.700 --> 03:29.770 third argument, then parameter profession will take relevant value. 03:30.290 --> 03:35.120 But if we miss that parameter, then it will take as a value programmer. 03:36.170 --> 03:43.520 So reload the page and we have the same result because the third argument is defined, but if we delete 03:43.520 --> 03:43.790 it. 03:45.020 --> 03:48.890 Then we will get programer as a value of profession. 03:49.610 --> 03:53.660 All right, this is the way how we could work with parameters in S5. 03:54.110 --> 03:58.300 Honestly, it wasn't so bad, but ethics offers us much better way. 03:58.970 --> 04:07.310 We don't need if statements or logical or operators anymore, we can simply assign the default values 04:07.310 --> 04:09.360 to parameters when we create them. 04:09.980 --> 04:23.410 So right here, first name equals to John, then assign Smith to last name and for profession. 04:24.050 --> 04:26.150 Right programmer. 04:28.680 --> 04:31.080 Also, delete the arguments below. 04:33.950 --> 04:41.660 Revolt and we have default parameter values and George Smith and I am programer, so those are default 04:41.660 --> 04:43.490 parameters with default values. 04:44.000 --> 04:54.890 But of course, if we insert here arguments, for example, as first name Niek, that though as last 04:54.890 --> 05:04.190 name and instructor for profession, then they will be overwritten to default values and will get I 05:04.190 --> 05:06.740 am Nito and I am instructor. 05:08.180 --> 05:11.800 So this is the main use case of default parameters in ethics. 05:12.200 --> 05:15.520 I'm not going to go further and write some crazy examples. 05:16.040 --> 05:19.310 I think it's quite enough to be able to use them in future. 05:19.970 --> 05:21.050 So let's move on.