WEBVTT 1 00:00:01.359 --> 00:00:02.270 In this lecture, 2 00:00:02.270 --> 00:00:04.444 we're gonna go back to the this keyword 3 00:00:04.444 --> 00:00:08.060 and learn how we can set the this keyword manually 4 00:00:08.060 --> 00:00:10.963 and also why we would want to do that. 5 00:00:12.195 --> 00:00:15.523 So let's say we are an airline again 6 00:00:15.523 --> 00:00:19.100 and in this case, Lufthansa, 7 00:00:19.100 --> 00:00:22.203 which is the biggest European airline group, by the way. 8 00:00:23.280 --> 00:00:26.410 And so let's create a very simple object 9 00:00:26.410 --> 00:00:31.410 for this airline with a very simple booking method as well. 10 00:00:34.120 --> 00:00:35.673 So we have the airline name. 11 00:00:36.520 --> 00:00:39.363 We have the code basically. 12 00:00:42.750 --> 00:00:46.093 We also want to keep an array of bookings. 13 00:00:47.010 --> 00:00:50.080 So also inside of the object, 14 00:00:50.080 --> 00:00:52.160 and then the book method. 15 00:00:52.160 --> 00:00:54.630 And remember from the previous section, 16 00:00:54.630 --> 00:00:57.880 I will now start using the way of writing methods, 17 00:00:57.880 --> 00:01:00.897 using the enhanced object literal syntax. 18 00:01:00.897 --> 00:01:05.897 And so that's simply by defining the method like this 19 00:01:06.010 --> 00:01:07.913 without having to write a function. 20 00:01:08.770 --> 00:01:11.710 So remember, before this, 21 00:01:11.710 --> 00:01:15.200 we used to do this, right? 22 00:01:15.200 --> 00:01:17.260 And if you still prefer this syntax, 23 00:01:17.260 --> 00:01:19.330 you can still do this one. 24 00:01:19.330 --> 00:01:22.940 But I do actually prefer the new syntax. 25 00:01:22.940 --> 00:01:25.653 And so I'll just start using this one now. 26 00:01:27.300 --> 00:01:29.340 So the flight number 27 00:01:29.340 --> 00:01:31.683 and also the passenger name here. 28 00:01:33.450 --> 00:01:35.873 So then let's log something to the console. 29 00:01:37.720 --> 00:01:40.930 And again, this could have been boilerplate code here 30 00:01:40.930 --> 00:01:45.223 but it's also good to practice writing this. 31 00:01:46.720 --> 00:01:51.463 So this should be a template string booked a seat on, 32 00:01:52.490 --> 00:01:55.700 so basically, we want to print like Jonas booked a seat 33 00:01:55.700 --> 00:01:57.837 on Lufthansa flight 34 00:01:57.837 --> 00:01:59.210 and then the flight number. 35 00:01:59.210 --> 00:02:02.440 And so here we are now going to get the airline name 36 00:02:02.440 --> 00:02:04.290 from the object. 37 00:02:04.290 --> 00:02:05.518 And so we already learned 38 00:02:05.518 --> 00:02:09.903 that for that, we use the this keyword, right? 39 00:02:11.858 --> 00:02:15.463 And then flight this.iataCode. 40 00:02:18.490 --> 00:02:20.020 So that's gonna be the LH 41 00:02:20.020 --> 00:02:22.130 and then the flight number itself 42 00:02:22.130 --> 00:02:23.853 that we pass into the function. 43 00:02:24.710 --> 00:02:26.307 So the flightNumber. 44 00:02:27.170 --> 00:02:29.760 So for now, this is just a nice review 45 00:02:29.760 --> 00:02:32.853 of how the this keyword works, right? 46 00:02:34.100 --> 00:02:36.540 And of course, I will now assume that you know 47 00:02:36.540 --> 00:02:37.950 how all of this works 48 00:02:37.950 --> 00:02:41.040 because otherwise, I will have to explain the same things 49 00:02:41.040 --> 00:02:43.000 over and over again. 50 00:02:43.000 --> 00:02:44.910 And so as I mentioned before, 51 00:02:44.910 --> 00:02:47.550 you should only progress once you really understand 52 00:02:47.550 --> 00:02:49.200 a certain topic. 53 00:02:49.200 --> 00:02:53.200 Anyway, let's now use the book function here. 54 00:02:53.200 --> 00:02:56.220 And I'll use the flight number 239 55 00:02:57.440 --> 00:02:59.963 and then with my own name. 56 00:03:01.350 --> 00:03:04.210 And let's right away book another Lufthansa flight 57 00:03:06.020 --> 00:03:11.003 for let's say Mike Smith on flight number 635. 58 00:03:12.830 --> 00:03:15.080 John Smith. 59 00:03:15.080 --> 00:03:17.930 And now, if we take a look at the results, 60 00:03:17.930 --> 00:03:22.930 then indeed, everything works just as expected, right? 61 00:03:23.840 --> 00:03:25.830 And so it's important to understand 62 00:03:25.830 --> 00:03:28.030 that the this keyword here points 63 00:03:28.030 --> 00:03:30.190 to the lufthansa object itself 64 00:03:30.190 --> 00:03:31.640 because that's the object 65 00:03:31.640 --> 00:03:34.990 on which the book method here was called. 66 00:03:34.990 --> 00:03:39.240 So again, that's just what I explained before, right? 67 00:03:39.240 --> 00:03:41.670 But now let's say that after some years, 68 00:03:41.670 --> 00:03:44.383 the Lufthansa Group created a new airline. 69 00:03:45.480 --> 00:03:48.910 So let's create eurowings here. 70 00:03:52.057 --> 00:03:53.757 And then a very similar object. 71 00:03:55.460 --> 00:03:58.403 So with the airline, the code. 72 00:04:00.660 --> 00:04:03.483 And also an empty bookings array. 73 00:04:06.160 --> 00:04:07.580 Okay? 74 00:04:07.580 --> 00:04:08.413 Oh, and by the way, 75 00:04:08.413 --> 00:04:11.840 we actually also want our book method here 76 00:04:11.840 --> 00:04:14.520 to add a new object to our bookings here. 77 00:04:14.520 --> 00:04:16.770 So that's super important as well. 78 00:04:16.770 --> 00:04:17.750 So I forget that. 79 00:04:17.750 --> 00:04:19.590 So let's go back here. 80 00:04:19.590 --> 00:04:21.610 So we will say again this 81 00:04:21.610 --> 00:04:22.960 and then the bookings array 82 00:04:24.280 --> 00:04:27.620 and then let's put a new object in there 83 00:04:27.620 --> 00:04:29.020 with the flight 84 00:04:30.020 --> 00:04:32.653 and so that's essentially gonna be this one. 85 00:04:33.750 --> 00:04:36.003 So the code plus the flight number. 86 00:04:40.150 --> 00:04:42.630 And then also the passenger name. 87 00:04:42.630 --> 00:04:46.143 And then let's quickly log that to the console here. 88 00:04:48.960 --> 00:04:52.090 So this.bookings is not a function 89 00:04:52.090 --> 00:04:54.339 and of course, it's not. 90 00:04:54.339 --> 00:04:57.153 We need the push method indeed. 91 00:04:58.470 --> 00:05:01.590 And so now you see that we have an array 92 00:05:01.590 --> 00:05:03.133 of our two bookings here. 93 00:05:05.000 --> 00:05:06.790 So that works perfectly. 94 00:05:06.790 --> 00:05:10.010 But now anyway, going back here to Eurowings, 95 00:05:10.010 --> 00:05:11.720 of course, we also want to be able 96 00:05:11.720 --> 00:05:15.290 to take bookings for a Eurowings flight, 97 00:05:15.290 --> 00:05:18.370 so as being this airline, right? 98 00:05:18.370 --> 00:05:21.110 Now, taking this exact same method here 99 00:05:21.110 --> 00:05:24.070 and simply copying it and pasting it here 100 00:05:24.070 --> 00:05:26.670 is a bad practice, right? 101 00:05:26.670 --> 00:05:29.240 So of course, we are not gonna do that. 102 00:05:29.240 --> 00:05:31.750 So instead, we will just take the method 103 00:05:31.750 --> 00:05:34.290 and store it in an external function. 104 00:05:34.290 --> 00:05:36.650 And then we can reuse that function 105 00:05:36.650 --> 00:05:38.453 for all of the different airlines. 106 00:05:39.520 --> 00:05:44.520 So what I mean is to create a new function called book 107 00:05:45.400 --> 00:05:50.357 and we will simply set it to lufthansa.book, all right? 108 00:05:52.860 --> 00:05:54.300 So again, this is possible 109 00:05:54.300 --> 00:05:57.630 because JavaScript has first class functions. 110 00:05:57.630 --> 00:06:01.260 And so we can simply take this function value here. 111 00:06:01.260 --> 00:06:03.730 So that's this function 112 00:06:03.730 --> 00:06:06.430 and then store it into a new variable, 113 00:06:06.430 --> 00:06:10.470 which is then gonna be also the book function, okay? 114 00:06:10.470 --> 00:06:13.460 Now, we could have written the function here also literally 115 00:06:13.460 --> 00:06:15.280 but that's just not necessary. 116 00:06:15.280 --> 00:06:16.680 We have it right here 117 00:06:16.680 --> 00:06:18.350 and so let's just leave it there 118 00:06:18.350 --> 00:06:21.160 and assign it to book right here. 119 00:06:21.160 --> 00:06:24.660 Okay, so let's try to use this book function 120 00:06:24.660 --> 00:06:27.230 to do a new booking now. 121 00:06:27.230 --> 00:06:30.150 But what do you think is gonna happen? 122 00:06:30.150 --> 00:06:35.150 So 23, and then let's say Sarah Williams 123 00:06:37.030 --> 00:06:38.520 and let's give it a save 124 00:06:38.520 --> 00:06:43.480 and now we get cannot read property airline of undefined. 125 00:06:43.480 --> 00:06:45.193 So do you know why this happened? 126 00:06:46.120 --> 00:06:48.710 Well, it's because this function here, 127 00:06:48.710 --> 00:06:52.030 the book function is now just a regular function call 128 00:06:52.030 --> 00:06:55.170 and so as we learned in one of the previous sections, 129 00:06:55.170 --> 00:06:56.427 in a regular function call, 130 00:06:56.427 --> 00:06:59.400 the this keyword points to undefined, 131 00:06:59.400 --> 00:07:02.070 at least in strict mode. 132 00:07:02.070 --> 00:07:03.086 All right? 133 00:07:03.086 --> 00:07:08.086 So once more, this book function is no longer this method. 134 00:07:08.900 --> 00:07:09.733 Okay? 135 00:07:09.733 --> 00:07:10.566 It's just not. 136 00:07:10.566 --> 00:07:13.400 It is now this separate function here. 137 00:07:13.400 --> 00:07:16.280 It's a copy of this one 138 00:07:16.280 --> 00:07:17.980 but it's not a method anymore, 139 00:07:17.980 --> 00:07:19.007 it's now a function. 140 00:07:19.007 --> 00:07:21.900 And so here it's a regular function call. 141 00:07:21.900 --> 00:07:25.130 And so therefore, the this keyword inside of it 142 00:07:25.130 --> 00:07:27.470 will now point to undefined. 143 00:07:27.470 --> 00:07:29.810 And that's why I kept telling you earlier 144 00:07:29.810 --> 00:07:32.610 that the this keyword depends on how the function 145 00:07:32.610 --> 00:07:34.410 is actually called. 146 00:07:34.410 --> 00:07:38.240 Okay, so make sure to understand these dynamics here. 147 00:07:38.240 --> 00:07:41.500 But now how do we actually fix this problem? 148 00:07:41.500 --> 00:07:44.870 So in other words, how do we tell JavaScript 149 00:07:44.870 --> 00:07:46.720 that we want to create a booking 150 00:07:46.720 --> 00:07:49.030 on the new Eurowings airline? 151 00:07:49.030 --> 00:07:51.290 Or even how do we tell it that we want 152 00:07:51.290 --> 00:07:53.980 to book on Lufthansa here? 153 00:07:53.980 --> 00:07:57.910 Well, basically, we need to tell JavaScript explicitly 154 00:07:57.910 --> 00:08:00.780 what the this keyword here should be like. 155 00:08:00.780 --> 00:08:03.320 So if we want to book a Lufthansa flight, 156 00:08:03.320 --> 00:08:06.190 the this keyword should point to Lufthansa 157 00:08:06.190 --> 00:08:09.620 but if we want to book a Eurowings flight, 158 00:08:09.620 --> 00:08:12.800 then the this keyword should point to Eurowings. 159 00:08:12.800 --> 00:08:14.370 So how do we do that? 160 00:08:14.370 --> 00:08:17.300 How do we tell JavaScript explicitly 161 00:08:17.300 --> 00:08:21.700 or manually what this this keyword should look like? 162 00:08:21.700 --> 00:08:24.890 Well, there are three function methods to do that 163 00:08:24.890 --> 00:08:28.550 and they are call, apply and bind. 164 00:08:28.550 --> 00:08:31.020 So when we first talked about the this keyword, 165 00:08:31.020 --> 00:08:33.700 I think I mentioned these methods back then 166 00:08:33.700 --> 00:08:35.300 and so now we're gonna use them, 167 00:08:35.300 --> 00:08:37.453 at least the call and apply methods. 168 00:08:38.790 --> 00:08:40.743 Okay, so let me show you how. 169 00:08:40.743 --> 00:08:43.870 So instead of just doing this, 170 00:08:43.870 --> 00:08:45.810 which doesn't work, 171 00:08:45.810 --> 00:08:47.983 let's actually comment that out. 172 00:08:48.930 --> 00:08:50.793 Does NOT work. 173 00:08:52.330 --> 00:08:57.330 So instead, we use book.call, all right? 174 00:08:57.440 --> 00:09:02.280 And remember that a function is really just an object 175 00:09:02.280 --> 00:09:04.390 and objects have methods 176 00:09:04.390 --> 00:09:07.370 and therefore, functions can have methods too 177 00:09:07.370 --> 00:09:09.573 and the call method is one of them. 178 00:09:10.670 --> 00:09:11.870 And in the call method, 179 00:09:11.870 --> 00:09:14.230 the first argument is exactly 180 00:09:14.230 --> 00:09:17.230 what we want the this keyword to point to. 181 00:09:17.230 --> 00:09:21.130 So let's say we want a Eurowings flight 182 00:09:21.130 --> 00:09:22.520 and then as usual, 183 00:09:22.520 --> 00:09:24.350 the rest of the arguments. 184 00:09:24.350 --> 00:09:29.350 So 23 and Sarah Williams. 185 00:09:29.400 --> 00:09:30.310 All right? 186 00:09:30.310 --> 00:09:34.800 And then let's log to the console also the eurowings object. 187 00:09:34.800 --> 00:09:38.320 Let's run this and then I'll explain a bit better 188 00:09:38.320 --> 00:09:39.393 what just happened. 189 00:09:40.270 --> 00:09:43.140 But indeed, we now have the bookings array 190 00:09:43.140 --> 00:09:45.270 and in there, we have the object 191 00:09:45.270 --> 00:09:49.710 with the EW23 and so EW comes from here. 192 00:09:49.710 --> 00:09:51.770 So exactly from the eurowings object 193 00:09:52.965 --> 00:09:54.900 and then also, of course, the name. 194 00:09:54.900 --> 00:09:57.227 And again, it is inside the bookings array 195 00:09:57.227 --> 00:09:59.083 of the Eurowings object. 196 00:10:00.270 --> 00:10:02.383 So let's recap what happened here. 197 00:10:03.460 --> 00:10:05.110 So this time, we did actually 198 00:10:05.110 --> 00:10:07.870 not call the book function ourselves. 199 00:10:07.870 --> 00:10:10.480 Instead, we called the call method 200 00:10:10.480 --> 00:10:12.210 and it's then this call method, 201 00:10:12.210 --> 00:10:14.610 which will call the book function 202 00:10:14.610 --> 00:10:18.230 with the this keyword set to eurowings. 203 00:10:18.230 --> 00:10:21.080 So whatever we pass has the first argument 204 00:10:21.080 --> 00:10:22.940 of the call method. 205 00:10:22.940 --> 00:10:25.280 And so this allows us to manually 206 00:10:25.280 --> 00:10:27.950 and explicitly set the this keyword 207 00:10:27.950 --> 00:10:30.770 of any function that we want to call. 208 00:10:30.770 --> 00:10:33.360 Then all the arguments after the first one 209 00:10:33.360 --> 00:10:36.800 are simply the arguments of the original function. 210 00:10:36.800 --> 00:10:38.510 And so in the case of the book function, 211 00:10:38.510 --> 00:10:41.000 of course, that's the flight number 212 00:10:41.000 --> 00:10:42.733 and the passenger name. 213 00:10:44.460 --> 00:10:47.863 And of course, now we can do the same also for Lufthansa. 214 00:10:49.020 --> 00:10:53.243 So book.call, this time with lufthansa 215 00:10:54.630 --> 00:10:58.213 and let's book someone else on flight 239. 216 00:11:02.210 --> 00:11:03.750 Let's say Mary Cooper 217 00:11:03.750 --> 00:11:08.557 and let's log again the lufthansa object 218 00:11:08.557 --> 00:11:10.763 but let's do it now here. 219 00:11:12.890 --> 00:11:15.210 And indeed, the string that we get here 220 00:11:15.210 --> 00:11:16.870 is completely correct 221 00:11:16.870 --> 00:11:21.670 and in here, so in the Lufthansa bookings array, 222 00:11:21.670 --> 00:11:24.373 we now have, of course, three bookings. 223 00:11:25.413 --> 00:11:26.370 Okay? 224 00:11:26.370 --> 00:11:29.000 And so that, of course, happened because this time, 225 00:11:29.000 --> 00:11:30.890 we set the this keyword inside 226 00:11:30.890 --> 00:11:33.843 of the function call to lufthansa. 227 00:11:34.770 --> 00:11:39.770 And so now this here is again back to pointing to Lufthansa, 228 00:11:39.940 --> 00:11:42.920 while before, right here, 229 00:11:42.920 --> 00:11:46.320 it was being pointed to Eurowings, all right? 230 00:11:46.320 --> 00:11:49.660 So even though the code of this function 231 00:11:49.660 --> 00:11:52.740 is inside of the lufthansa object, 232 00:11:52.740 --> 00:11:56.370 we made it so that the this keyword in here 233 00:11:56.370 --> 00:11:58.820 pointed to eurowings. 234 00:11:58.820 --> 00:12:03.460 So to this object, this new one right here, okay? 235 00:12:03.460 --> 00:12:04.450 So we have a way now 236 00:12:04.450 --> 00:12:07.484 of manually manipulating the this keyword 237 00:12:07.484 --> 00:12:09.530 using the call method. 238 00:12:09.530 --> 00:12:11.860 And of course, we could now keep going 239 00:12:11.860 --> 00:12:15.027 and create more airlines into the Lufthansa Group, 240 00:12:15.027 --> 00:12:17.423 like the Swiss Air Lines. 241 00:12:23.115 --> 00:12:23.948 Air Lines. 242 00:12:25.040 --> 00:12:27.770 Now, of course, these property names, 243 00:12:27.770 --> 00:12:31.800 they all need to have the exact same format 244 00:12:31.800 --> 00:12:34.230 as this original object here 245 00:12:34.230 --> 00:12:38.720 because this method is trying to read just these properties. 246 00:12:38.720 --> 00:12:40.820 So it's always iataCode 247 00:12:40.820 --> 00:12:44.560 and bookings, as you see here, and airline. 248 00:12:44.560 --> 00:12:45.580 And so of course, 249 00:12:45.580 --> 00:12:49.480 we need to use exactly these property names here as well 250 00:12:51.120 --> 00:12:52.420 but just like this, 251 00:12:52.420 --> 00:12:54.300 we can now go ahead 252 00:12:54.300 --> 00:12:58.443 and use our book function on the Swiss Air Line. 253 00:13:00.070 --> 00:13:02.660 And so this time, we will set the this keyword 254 00:13:02.660 --> 00:13:06.163 in the book.call to the swiss object. 255 00:13:07.250 --> 00:13:12.250 583 and let's book another flight for Mary Cooper here. 256 00:13:18.500 --> 00:13:20.473 And indeed, it worked again. 257 00:13:21.600 --> 00:13:25.323 So here is the booking again. 258 00:13:26.390 --> 00:13:27.390 Okay? 259 00:13:27.390 --> 00:13:29.510 There's just some weird thing here 260 00:13:30.600 --> 00:13:33.380 and so oh, actually here, 261 00:13:33.380 --> 00:13:35.120 it needs to be airline as well. 262 00:13:35.120 --> 00:13:39.620 So I was telling you you need to use the same property names 263 00:13:39.620 --> 00:13:42.070 and I wasn't even doing it myself. 264 00:13:42.070 --> 00:13:46.290 So it needs to be airline, just like it is here 265 00:13:47.250 --> 00:13:48.763 and the same here too. 266 00:13:51.150 --> 00:13:53.993 And now the string is, of course, correct here. 267 00:13:55.480 --> 00:13:56.860 Okay. 268 00:13:56.860 --> 00:13:58.573 Let me add a comment here. 269 00:14:00.160 --> 00:14:03.000 Call method because in fact, 270 00:14:03.000 --> 00:14:05.890 there is a similar method to the call method, 271 00:14:05.890 --> 00:14:09.530 which is called the apply method. 272 00:14:09.530 --> 00:14:13.560 And the apply method does basically exactly the same thing. 273 00:14:13.560 --> 00:14:15.720 The only difference is that apply 274 00:14:15.720 --> 00:14:18.290 does not receive a list of arguments 275 00:14:18.290 --> 00:14:19.723 after the this keyword, 276 00:14:20.710 --> 00:14:23.160 so it doesn't receive this list here 277 00:14:23.160 --> 00:14:25.300 but instead, it's gonna take an array 278 00:14:25.300 --> 00:14:27.697 of the arguments, okay? 279 00:14:27.697 --> 00:14:29.970 And so it will then take the elements 280 00:14:29.970 --> 00:14:33.670 from that array and pass it into the function. 281 00:14:33.670 --> 00:14:34.570 So let's say 282 00:14:37.003 --> 00:14:37.920 flightData, 283 00:14:39.190 --> 00:14:41.540 so I'm just gonna create quickly an array here 284 00:14:41.540 --> 00:14:44.850 with the flight number and the passenger name. 285 00:14:44.850 --> 00:14:49.800 So book on the same flight George Cooper 286 00:14:50.900 --> 00:14:54.703 and now we can use apply on the book function. 287 00:14:55.610 --> 00:14:56.823 So apply. 288 00:14:57.870 --> 00:15:00.990 And then just as here in the call method, 289 00:15:00.990 --> 00:15:03.783 the first argument is the this keyword. 290 00:15:05.200 --> 00:15:06.950 But now the second argument, 291 00:15:06.950 --> 00:15:10.333 it needs to be as I just said an array of data. 292 00:15:11.180 --> 00:15:13.963 So let's pass in the flightData array here. 293 00:15:15.410 --> 00:15:17.010 But then let's just take a look. 294 00:15:18.180 --> 00:15:20.313 I'll just take this one here actually. 295 00:15:24.200 --> 00:15:27.820 And so indeed, here it worked again. 296 00:15:27.820 --> 00:15:29.220 All right? 297 00:15:29.220 --> 00:15:32.060 This apply method is not that used anymore 298 00:15:32.060 --> 00:15:34.660 in modern JavaScript because now, 299 00:15:34.660 --> 00:15:39.130 we actually have a better way of doing the exact same thing. 300 00:15:39.130 --> 00:15:41.163 And do you know what I'm talking about? 301 00:15:42.120 --> 00:15:44.830 So let me show it to you. 302 00:15:44.830 --> 00:15:49.260 Book.call, so instead of using apply, 303 00:15:49.260 --> 00:15:51.740 we can still use call, 304 00:15:51.740 --> 00:15:53.540 again with swiss 305 00:15:53.540 --> 00:15:56.770 and then we can simply use the spread operator 306 00:15:56.770 --> 00:15:59.227 to take the data out of flightData 307 00:16:00.090 --> 00:16:02.430 and basically put them here. 308 00:16:02.430 --> 00:16:06.050 So this here is the same as this one. 309 00:16:06.050 --> 00:16:08.780 And so right now, with modern JavaScript, 310 00:16:08.780 --> 00:16:12.140 I prefer to just always use the call method 311 00:16:12.140 --> 00:16:16.773 and then spread out the arguments from an array like this. 312 00:16:18.300 --> 00:16:22.523 So again, this here is exactly the same as this. 313 00:16:23.720 --> 00:16:27.260 So in summary, we now have yet another tool 314 00:16:27.260 --> 00:16:29.210 in our toolbox here 315 00:16:29.210 --> 00:16:31.450 and this one is one that allows us 316 00:16:31.450 --> 00:16:34.820 to explicitly define the this keyword 317 00:16:34.820 --> 00:16:36.890 in any function that we want. 318 00:16:36.890 --> 00:16:39.260 But there is actually yet another method 319 00:16:39.260 --> 00:16:41.520 which allows us to do the same thing 320 00:16:41.520 --> 00:16:43.530 and that's the bind method. 321 00:16:43.530 --> 00:16:44.363 It's more important actually 322 00:16:44.363 --> 00:16:46.740 than the call and apply methods, 323 00:16:46.740 --> 00:16:49.053 so I'm gonna leave it for the next lecture.