1 00:00:00,920 --> 00:00:04,580 There's one last quick thing I want to mention around functions, so down here at the very bottom, 2 00:00:04,580 --> 00:00:06,700 we're going to add in one last example here. 3 00:00:07,250 --> 00:00:10,700 Let's imagine for a second, do we have some object that describes today's weather? 4 00:00:10,970 --> 00:00:17,020 So maybe we call it forecast like so and maybe it's got a date to indicate today's date and the current 5 00:00:17,030 --> 00:00:17,930 weather outside. 6 00:00:18,000 --> 00:00:20,720 So maybe that will be a string that we'll call Sunny like so. 7 00:00:22,020 --> 00:00:26,310 Now, let's try creating a function that's going to take that forecast and just log out the weather, 8 00:00:26,850 --> 00:00:33,210 so to do so, we could say something like const log weather and then we're going to get some forecast 9 00:00:33,210 --> 00:00:33,870 object. 10 00:00:35,000 --> 00:00:39,950 We need to annotate the return type of the argument type right here, so to do so, we would put in 11 00:00:39,950 --> 00:00:45,440 an object literal, just like we saw previously with our variable annotation, like what we saw right 12 00:00:45,440 --> 00:00:45,740 here. 13 00:00:47,070 --> 00:00:52,200 So we would put in a colon and then curly braces and list out all the different properties that we would 14 00:00:52,200 --> 00:00:54,000 expect this forecast object to have. 15 00:00:54,660 --> 00:01:00,330 So maybe it will be a date that has a date type and a weather that has a string type. 16 00:01:00,920 --> 00:01:03,150 And zoom out for just a second so you can see that whole line. 17 00:01:04,459 --> 00:01:09,140 Then after the list right there, I'm only going to try to log out the current weather so there's not 18 00:01:09,140 --> 00:01:13,910 going to be anything I'm going to return, so I'll mark the return type is void and then put down my 19 00:01:13,910 --> 00:01:15,770 arrow for the function like so. 20 00:01:18,820 --> 00:01:19,720 I'm going to zoom back in. 21 00:01:20,430 --> 00:01:27,340 So now if we wanted to, we could do a quick control log of forecast dot date and a console log of, 22 00:01:27,340 --> 00:01:30,580 say, forecast, not weather like so. 23 00:01:32,690 --> 00:01:38,150 And then just as a quick example down here, we could try calling log weather with the forecast object 24 00:01:38,810 --> 00:01:42,470 and just to make the variables in here a little bit more clear, maybe rather than calling this forecast, 25 00:01:42,470 --> 00:01:44,330 it should be like today's weather. 26 00:01:44,360 --> 00:01:45,790 Maybe that makes a little bit more sense. 27 00:01:49,880 --> 00:01:55,100 All right, now, one little optimization we could do here would be to use a little bit of 2015 syntax 28 00:01:55,250 --> 00:02:00,860 and attempt to restructure the dates and whether properties out of the forecast variable right there. 29 00:02:01,670 --> 00:02:06,380 So in other words, rather than having to refer to forecast update and forecast out whether I want to 30 00:02:06,380 --> 00:02:12,800 just pull those two properties directly off inside the argument list, if we were using normal E 2015 31 00:02:12,800 --> 00:02:14,660 syntax, I'll put a quick example right here. 32 00:02:14,810 --> 00:02:16,070 We would write out something like this. 33 00:02:16,070 --> 00:02:17,840 We would say const log whether. 34 00:02:20,210 --> 00:02:24,830 And then inside the argument list, we would put a set of curly braces and list the two properties we 35 00:02:24,830 --> 00:02:25,850 wanted to access. 36 00:02:25,880 --> 00:02:29,060 So in this case, date and weather like so. 37 00:02:29,510 --> 00:02:31,940 And then we could do a simple console log of date. 38 00:02:33,120 --> 00:02:37,260 And of weather, so how do we use this kind of syntax right here? 39 00:02:38,170 --> 00:02:39,800 With a typescript invitation. 40 00:02:40,600 --> 00:02:44,800 All right, I'm going to remove the 2015 and we're going to adjust the syntax in here just a little 41 00:02:44,800 --> 00:02:45,090 bit. 42 00:02:45,790 --> 00:02:50,440 So if we ever want to use these structuring along with an annotation, all we have to do is replace 43 00:02:50,440 --> 00:02:53,350 the variable itself with the actual structuring statement. 44 00:02:53,990 --> 00:02:59,170 So instead of forecast right there, I'm going to replace it with a set of curly braces and I'll list 45 00:02:59,170 --> 00:03:02,080 out the different properties I want to pull out of that object. 46 00:03:02,500 --> 00:03:03,130 So be a date. 47 00:03:03,130 --> 00:03:08,440 And whether like so and then I can adjust the body, the function to be just date and whether. 48 00:03:09,520 --> 00:03:16,180 So notice that we did not try to stick the annotation types along with the structuring, the D structuring 49 00:03:16,180 --> 00:03:21,670 portion and the annotation are always going to be two separate statements separated by that colon right 50 00:03:21,670 --> 00:03:21,940 there. 51 00:03:22,390 --> 00:03:27,220 So we're first going to do our restructuring and then we'll try to do the actual annotation right after 52 00:03:27,220 --> 00:03:27,430 it. 53 00:03:28,780 --> 00:03:32,770 All right, so now we've seen that another quick pause right here and we'll move on to our last subject 54 00:03:32,770 --> 00:03:34,870 around annotations and inference.