1 00:00:00,950 --> 00:00:01,819 All right. 2 00:00:01,819 --> 00:00:04,730 We come back in this video. 3 00:00:04,820 --> 00:00:07,510 Let's get started with functions. 4 00:00:07,520 --> 00:00:14,540 But before we get into that, we need to know the syntax of a function where we have couple of ways 5 00:00:14,540 --> 00:00:17,390 of declaring or creating a function. 6 00:00:17,630 --> 00:00:22,670 The first one that you talk about is called function declaration. 7 00:00:23,370 --> 00:00:30,750 So as always, we need to bring in our function keyword. 8 00:00:30,750 --> 00:00:33,310 This one is from JavaScript. 9 00:00:33,330 --> 00:00:36,750 You bring in your function keyword. 10 00:00:37,260 --> 00:00:37,580 Okay? 11 00:00:37,860 --> 00:00:43,680 And then the next one here is going to be the name of your function, function name. 12 00:00:44,130 --> 00:00:47,640 And then a function would take in what is called parameters. 13 00:00:47,690 --> 00:00:53,490 Then we have our cases here, and then our code to be executed lies in this. 14 00:00:53,910 --> 00:00:59,340 So let's let me show you with code to better understand what a function is all about. 15 00:00:59,580 --> 00:01:03,540 As usual, because we are starting a new concept. 16 00:01:03,540 --> 00:01:13,620 I have created a new project or folder for it and I have name it as functions that is functions over 17 00:01:13,620 --> 00:01:23,490 here and inside I have one HTML and then with the head each one functions over there and have required 18 00:01:23,490 --> 00:01:25,170 my JavaScript inside that. 19 00:01:25,170 --> 00:01:32,550 So let me close this one and now let's start with function that is JavaScript here. 20 00:01:33,090 --> 00:01:37,560 So we have couple of ways of defining a function. 21 00:01:37,560 --> 00:01:43,530 So come here says ways of declaring or creating a function. 22 00:01:43,530 --> 00:01:44,730 Ways of creating. 23 00:01:45,620 --> 00:01:46,550 A function. 24 00:01:47,550 --> 00:01:49,440 And we have two ways. 25 00:01:49,440 --> 00:01:52,590 One is using the function. 26 00:01:53,420 --> 00:01:54,420 Declaration. 27 00:01:56,420 --> 00:01:59,660 And then the other one is called function. 28 00:02:02,020 --> 00:02:03,070 Expression. 29 00:02:03,610 --> 00:02:04,420 So. 30 00:02:05,550 --> 00:02:15,420 In this video, let's have a look at a simple function that add two numbers together for now, not add, 31 00:02:15,420 --> 00:02:21,240 let's say, a function to say or to greet somebody say let's say hello. 32 00:02:21,240 --> 00:02:22,200 You are welcome. 33 00:02:22,380 --> 00:02:25,860 And we're going to display that one inside the console. 34 00:02:26,280 --> 00:02:33,420 So let's say create a function to say hello. 35 00:02:34,620 --> 00:02:40,830 JS That so as you remember from here to create that we bring in our function keyword. 36 00:02:40,830 --> 00:02:44,550 So here we go, function keyword here. 37 00:02:44,730 --> 00:02:49,980 The next one is the name of my function as a variable name. 38 00:02:50,100 --> 00:02:55,410 So the name of a function must depict what it does. 39 00:02:55,410 --> 00:03:01,140 So we say say hello, that our function name is that I'm using common cases. 40 00:03:01,380 --> 00:03:07,650 So depending how you want to name your variables, as we discussed before, that is my function name 41 00:03:07,980 --> 00:03:09,120 and my. 42 00:03:10,230 --> 00:03:11,340 Brackets here. 43 00:03:11,610 --> 00:03:16,920 So then I bring my body here as that, and then my carry braces. 44 00:03:17,250 --> 00:03:18,870 That is a function. 45 00:03:18,990 --> 00:03:21,990 Again, this is what you call function declaration. 46 00:03:21,990 --> 00:03:22,830 So let me. 47 00:03:23,650 --> 00:03:24,850 Bring it here. 48 00:03:25,000 --> 00:03:28,330 As call function decoration. 49 00:03:28,360 --> 00:03:30,580 This what you call function decoration. 50 00:03:30,580 --> 00:03:35,650 So inside the codebases is where your code will be here. 51 00:03:36,100 --> 00:03:39,280 So a function to say hello. 52 00:03:40,920 --> 00:03:42,120 So in the body. 53 00:03:42,150 --> 00:03:43,710 That's where I'm going with our logic. 54 00:03:43,710 --> 00:03:49,950 So we just want to console, log, simple message, console, log and say. 55 00:03:51,690 --> 00:03:52,560 Hello. 56 00:03:53,190 --> 00:03:55,920 Work on two functions. 57 00:03:58,440 --> 00:03:59,310 That is it. 58 00:03:59,340 --> 00:04:03,120 So I have created my first function. 59 00:04:03,740 --> 00:04:07,670 So how can I use this particular function? 60 00:04:07,880 --> 00:04:11,210 And that is what you call function invocation. 61 00:04:11,570 --> 00:04:17,029 Meaning calling a function is called function invocation. 62 00:04:17,269 --> 00:04:25,280 So as soon as you create a function well, we have saved the function called say hello in memory of 63 00:04:25,280 --> 00:04:26,180 JavaScript. 64 00:04:26,660 --> 00:04:30,560 So anywhere I want to use this message. 65 00:04:31,600 --> 00:04:35,410 If I call my function, I will say hello. 66 00:04:35,440 --> 00:04:37,200 Welcome to function. 67 00:04:37,210 --> 00:04:44,290 So if I check my calls, the function or what is function is doing that just display this message to 68 00:04:44,290 --> 00:04:45,160 the console. 69 00:04:45,190 --> 00:04:46,840 That's a basic function. 70 00:04:46,840 --> 00:04:48,670 So to be able to view. 71 00:04:48,700 --> 00:04:50,590 Let's open the console. 72 00:04:50,620 --> 00:04:53,860 And now we see that well, this is where. 73 00:04:53,860 --> 00:04:54,260 Right. 74 00:04:54,280 --> 00:04:59,650 Nothing has been shown here because we have not called the function. 75 00:05:00,010 --> 00:05:05,350 So after we create a function, we need to call it or invoke. 76 00:05:05,380 --> 00:05:09,250 So here is create a function here. 77 00:05:10,640 --> 00:05:15,050 And then if you don't call it well, the function will not do anything. 78 00:05:15,080 --> 00:05:19,160 So down here, let's say, calling a function. 79 00:05:20,100 --> 00:05:26,220 Or is our system as function invocation won't invoke the function? 80 00:05:26,250 --> 00:05:28,890 How do we invoke a function? 81 00:05:29,520 --> 00:05:32,070 So to be able to know that. 82 00:05:33,080 --> 00:05:35,080 Certain variable is a function. 83 00:05:35,090 --> 00:05:36,290 Let me show you the clue. 84 00:05:36,410 --> 00:05:40,250 So here to call the function, you bring in your function name. 85 00:05:40,580 --> 00:05:42,110 That is, say hello. 86 00:05:42,800 --> 00:05:44,480 If I do this one, I save it. 87 00:05:44,570 --> 00:05:46,760 So nothing has been shown here. 88 00:05:47,030 --> 00:05:51,920 So to call a function, you need to bring your. 89 00:05:54,140 --> 00:05:56,900 Brackets like that. 90 00:05:56,930 --> 00:05:59,900 Now, with this one, if I save this one. 91 00:06:00,050 --> 00:06:03,260 Now, if you see that, I have. 92 00:06:03,470 --> 00:06:04,080 Hello. 93 00:06:04,100 --> 00:06:05,570 Welcome to function. 94 00:06:05,570 --> 00:06:07,790 Because I have called a function. 95 00:06:08,060 --> 00:06:08,540 Meaning? 96 00:06:08,540 --> 00:06:12,260 I have my square bracket here. 97 00:06:12,500 --> 00:06:14,590 Meaning calling the function. 98 00:06:14,600 --> 00:06:22,400 So anything that we see a variable with this square bracket around it, it tells you it's a function. 99 00:06:22,940 --> 00:06:29,540 So you can see that even console dot now no console dot log. 100 00:06:30,530 --> 00:06:32,860 How will we see about this? 101 00:06:33,230 --> 00:06:39,170 This is a function because look at the curves, the square bracket here we have the square bracket here, 102 00:06:39,170 --> 00:06:41,330 which means it's a function. 103 00:06:41,960 --> 00:06:47,050 So that is pretty much it about how we can create a function, the first one. 104 00:06:47,060 --> 00:06:48,470 Now let's move step by step. 105 00:06:48,650 --> 00:06:54,830 First of all, we knew how to create a function and then we knew how to call a function. 106 00:06:55,400 --> 00:06:59,600 That's the first step about function declaration. 107 00:07:00,410 --> 00:07:03,170 What about function expression? 108 00:07:03,410 --> 00:07:04,820 Where's my function expression? 109 00:07:04,820 --> 00:07:05,170 Yeah. 110 00:07:05,180 --> 00:07:06,230 Here is step number two. 111 00:07:06,230 --> 00:07:09,320 How can we create function expression? 112 00:07:09,500 --> 00:07:11,420 So here is my function. 113 00:07:12,640 --> 00:07:14,110 Expression, perfect. 114 00:07:14,110 --> 00:07:18,100 So how can we create that kind of function function? 115 00:07:18,760 --> 00:07:24,580 So for function expression, we assign a function to a variable. 116 00:07:24,880 --> 00:07:27,460 So the name of this function. 117 00:07:28,290 --> 00:07:31,080 Let me comment about this one or let me leave it. 118 00:07:31,560 --> 00:07:41,580 So this function is going to also, I mean, displace a message and say, yes, I mean, good morning. 119 00:07:41,580 --> 00:07:42,060 Yes. 120 00:07:42,060 --> 00:07:44,490 Just grid a function to grid. 121 00:07:44,520 --> 00:07:45,180 Okay. 122 00:07:45,180 --> 00:07:49,110 So here you bring in your name calling. 123 00:07:49,130 --> 00:07:51,330 So let me show you with this picture here. 124 00:07:51,900 --> 00:07:54,660 So we call this one function expression. 125 00:07:54,720 --> 00:08:04,380 We have our keyword here led and then we have a variable name equal to the function keyword and then 126 00:08:04,380 --> 00:08:11,550 our square bracket and a function body as compared to function declaration we don't have let's we don't 127 00:08:11,550 --> 00:08:17,400 have equal to that is function declaration and this function expression. 128 00:08:17,610 --> 00:08:26,970 So here a function going to be grading I'm going to do somebody and then assign to equal to the name 129 00:08:26,970 --> 00:08:31,860 of my function and my square bracket and my carry basis. 130 00:08:31,860 --> 00:08:38,250 So in here I just console.log something and say good morning. 131 00:08:39,530 --> 00:08:40,270 Perfect. 132 00:08:40,280 --> 00:08:44,890 So let me comment this one out because I don't want to call this function. 133 00:08:44,900 --> 00:08:52,100 So if I save it now, my console is empty because I haven't called this function. 134 00:08:52,100 --> 00:08:58,040 So the way we call function declaration, it is same as calling function expression. 135 00:08:58,250 --> 00:09:02,840 So here I would just bring in my greeting and then call my function. 136 00:09:02,870 --> 00:09:05,630 I start and now I have. 137 00:09:05,630 --> 00:09:06,740 Good morning. 138 00:09:06,770 --> 00:09:10,070 So before we end this video, just have a look. 139 00:09:10,070 --> 00:09:16,490 The two ways of creating a function function, the creation and then function expression. 140 00:09:16,850 --> 00:09:19,400 And after creating, we need to call the function. 141 00:09:19,400 --> 00:09:23,030 These are the two things you need to take note in this particular video. 142 00:09:23,090 --> 00:09:26,060 So let me give you an exercise. 143 00:09:26,570 --> 00:09:26,960 Okay. 144 00:09:26,990 --> 00:09:29,330 So exercise is like this one. 145 00:09:29,600 --> 00:09:35,660 Create a function to greet your mom. 146 00:09:36,480 --> 00:09:38,910 Can say Hello Mom. 147 00:09:38,940 --> 00:09:41,940 Good morning or Hello, Mom, how are you? 148 00:09:42,370 --> 00:09:42,720 Okay. 149 00:09:42,720 --> 00:09:43,800 So create. 150 00:09:44,700 --> 00:09:46,380 Create a function. 151 00:09:47,770 --> 00:09:48,910 To greet Mom. 152 00:09:50,270 --> 00:09:52,910 That is it to any message you want you to get your mom? 153 00:09:52,910 --> 00:09:54,350 Why not go ahead and do it? 154 00:09:54,440 --> 00:09:59,060 So here you can give your function a name the way you want it. 155 00:09:59,060 --> 00:10:02,490 But a name must be descriptive and then just console.log. 156 00:10:02,510 --> 00:10:04,130 I mean, Mom, how are you? 157 00:10:04,160 --> 00:10:04,760 Good morning. 158 00:10:04,760 --> 00:10:05,750 I miss you. 159 00:10:05,780 --> 00:10:06,890 Something like that. 160 00:10:06,890 --> 00:10:08,620 So let's see how you're going to do this one. 161 00:10:08,630 --> 00:10:09,120 In this video. 162 00:10:09,120 --> 00:10:14,480 And in this video, you solve it and talk about another key concept when you come to function. 163 00:10:14,480 --> 00:10:15,440 The next video.