1 00:00:05,120 --> 00:00:08,900 Welcome back, everyone, to this lecture, we're going to discuss selectors. 2 00:00:10,210 --> 00:00:15,970 We've seen already that we can use divs and Spann's to create containers that apply styling to only 3 00:00:15,970 --> 00:00:18,460 certain elements within those dips and spans. 4 00:00:18,700 --> 00:00:24,250 Even if they share the same tech like a paragraph outside of a div versus a paragraph inside a div, 5 00:00:24,730 --> 00:00:30,610 however, we can use selectors like Class An ID to have a lot more control and flexibility over this. 6 00:00:31,870 --> 00:00:36,730 Let's imagine a situation where class and it would be very useful to us more than what we can do with 7 00:00:36,730 --> 00:00:37,510 just a div. 8 00:00:37,840 --> 00:00:39,700 Imagine the following HTML code. 9 00:00:40,090 --> 00:00:41,740 I have three paragraphs here. 10 00:00:42,220 --> 00:00:45,400 Two are outside the div and one is inside the div. 11 00:00:45,550 --> 00:00:47,950 I can see the text says outside div. 12 00:00:47,980 --> 00:00:52,120 The next text says inside div and then the third text says also outside div. 13 00:00:52,630 --> 00:00:59,710 Now imagine I wanted to apply some sort of unique styling to each individual paragraph, so I want these 14 00:00:59,710 --> 00:01:05,200 three paragraphs to each have their own unique text color, for instance, right now with the use of 15 00:01:05,200 --> 00:01:06,550 divs and span's. 16 00:01:06,760 --> 00:01:08,320 We don't really have a good way to do this. 17 00:01:08,860 --> 00:01:14,950 I right now have separated out the paragraphs from being inside the device, but then I also have a 18 00:01:14,950 --> 00:01:19,720 paragraph tag within the div, and I'm not really sure yet which one's going to be more specific. 19 00:01:19,930 --> 00:01:25,990 So I'm running into a bit of a conundrum here where I can't figure out a way, even with divs, to uniquely 20 00:01:25,990 --> 00:01:28,780 style each of the three paragraphs. 21 00:01:29,050 --> 00:01:31,630 This is where classes and ideas can come to help us. 22 00:01:32,830 --> 00:01:37,990 So we can assign elements a class attribute with a specific name for CIUSSS purposes. 23 00:01:38,410 --> 00:01:43,990 Classes are typically use friendships to group the styling everything inside the div container together 24 00:01:44,380 --> 00:01:48,040 and classes can be repeatedly used across a web page across elements. 25 00:01:49,020 --> 00:01:55,140 Then there's also an ID attribute, which can be used to also connect for CSA styling, but the IDs 26 00:01:55,140 --> 00:01:59,580 should be completely unique and used for only a single element on the web page. 27 00:01:59,850 --> 00:02:03,870 So classes you can use more than once and for many different types of elements. 28 00:02:04,080 --> 00:02:07,710 IDs should be unique for that particular element that you want to style. 29 00:02:08,009 --> 00:02:15,450 Let's revisit our HTML example, where I want to apply some sort of CSS styling to each individual paragraph 30 00:02:15,450 --> 00:02:17,730 that is different and unrelated to each other. 31 00:02:18,300 --> 00:02:23,760 What I could do is for the paragraphs that are outside the div is assign them a unique ID. 32 00:02:24,900 --> 00:02:32,550 So what I do is inside the HTML, I create an ID attribute and assign it to a unique value. 33 00:02:32,910 --> 00:02:37,690 Notice how the first paragraph tag has an ID equal to the value one. 34 00:02:37,710 --> 00:02:38,770 That's just a string code. 35 00:02:38,790 --> 00:02:44,880 You can choose and then at the very bottom outside the div, I have the paragraph with the ID attribute 36 00:02:44,880 --> 00:02:45,720 equal to two. 37 00:02:46,080 --> 00:02:51,420 I cannot use this as unique identifiers for those specific paragraphs, so I don't need to worry about 38 00:02:51,420 --> 00:02:54,900 having to assign some text color to all paragraph elements. 39 00:02:55,110 --> 00:02:59,880 I can now assign it to the specific IDs, then for something like a div. 40 00:03:00,150 --> 00:03:06,420 If I wanted to style everything inside that div, I could assign that a class and the class is something 41 00:03:06,420 --> 00:03:08,520 I can use over and over again on the web page. 42 00:03:08,760 --> 00:03:13,950 So if I create another div on this web page, it's OK for me to assign it to the same class. 43 00:03:14,400 --> 00:03:21,600 And note now I have three essentially unique ways of grabbing these elements and assigning them styles. 44 00:03:21,840 --> 00:03:27,600 So now CIUSSS is going to be able to actually style these paragraphs different things like different 45 00:03:27,600 --> 00:03:28,260 text colors. 46 00:03:29,100 --> 00:03:33,120 So let's check this out in HTML and CSS in order to really understand it. 47 00:03:34,090 --> 00:03:34,360 All right. 48 00:03:34,390 --> 00:03:36,670 Here I am back inside our code editor. 49 00:03:37,000 --> 00:03:41,560 Let's go ahead and delete some of the CSIS that we created from the previous lecture. 50 00:03:41,890 --> 00:03:43,330 And I'm also going to. 51 00:03:44,230 --> 00:03:44,770 Delete. 52 00:03:46,140 --> 00:03:51,450 The HTML code lets actually create the same situation we had previously in those slides, so I'm going 53 00:03:51,450 --> 00:03:58,950 to say above the div for a paragraph tag, then I'll create a div and inside this div I'll create some, 54 00:03:58,950 --> 00:04:00,450 Texas says inside the div. 55 00:04:02,080 --> 00:04:06,100 And then what I'll say here is create another paragraph that says. 56 00:04:07,200 --> 00:04:08,010 Below that, if. 57 00:04:09,070 --> 00:04:16,000 OK, so it looks like the same here in the output, but clearly we want to be able to add styling to 58 00:04:16,000 --> 00:04:17,079 each of these paragraphs. 59 00:04:17,290 --> 00:04:17,950 How can I do that? 60 00:04:18,399 --> 00:04:25,330 Well, I can make use of things like classes and IDs, so classes typically go with divs and we can't 61 00:04:25,330 --> 00:04:26,200 actually reuse them. 62 00:04:26,650 --> 00:04:31,870 So we're going to say class is equal to let's create a string here called my class. 63 00:04:32,560 --> 00:04:36,190 Now the question is, how do we actually refer to my class here? 64 00:04:36,580 --> 00:04:41,140 Previously, we were referring to elements just by their name, something like Div, and then I would 65 00:04:41,140 --> 00:04:44,110 say something like color for text. 66 00:04:45,110 --> 00:04:47,870 And maybe use Orange, for instance. 67 00:04:48,410 --> 00:04:54,890 OK, so that's one way I could do it, but if I want to only apply it to this specific div, so I'm 68 00:04:54,890 --> 00:05:02,480 actually going to create a div here, and let's also create a paragraph that says 2nd div. 69 00:05:02,780 --> 00:05:05,540 Notice the second div is orange as well. 70 00:05:06,050 --> 00:05:12,710 So maybe what I want to do is instead of using the div, I'll only use the class to tell CST, Are you 71 00:05:12,710 --> 00:05:13,610 using a class? 72 00:05:13,670 --> 00:05:20,390 Use a period first and then you type out the class name, which in our case was my class. 73 00:05:20,870 --> 00:05:25,130 Then you have your curly braces and you can assign the styling like color red. 74 00:05:26,010 --> 00:05:29,760 And note now, since I'm only referring to my class. 75 00:05:30,150 --> 00:05:36,780 Notice how only that first div paragraph and everything inside of that div is going to have that text 76 00:05:36,780 --> 00:05:42,120 color read, but it doesn't affect any of the other paragraphs or any of the other dibbs because I'm 77 00:05:42,120 --> 00:05:48,930 only referring to my class if I connect that class to this other div by saying something like class 78 00:05:49,440 --> 00:05:51,790 is equal to my class. 79 00:05:51,810 --> 00:05:54,060 You'll notice then it's actually connected. 80 00:05:54,480 --> 00:06:00,360 So that is how a class works and the difference between a class versus an ID that we're about to see 81 00:06:00,570 --> 00:06:02,520 is that class is expected. 82 00:06:02,940 --> 00:06:06,570 It's OK to use it multiple times on the same web page. 83 00:06:06,990 --> 00:06:12,690 If you want something that is a unique identifier for just a specific instance of an element. 84 00:06:12,960 --> 00:06:14,010 That's where you use it. 85 00:06:14,640 --> 00:06:18,540 So I can say something like ID and set this idea equal to one. 86 00:06:19,110 --> 00:06:25,680 Then if I want to actually apply styling to the ID element one, I come back to master's thesis. 87 00:06:26,610 --> 00:06:33,570 And then the next item I can do for an ID is you use a hashtag so ID selectors use hashtags and there 88 00:06:33,570 --> 00:06:35,910 are to single out an estimate element. 89 00:06:36,300 --> 00:06:38,460 So we named that ID one. 90 00:06:39,480 --> 00:06:43,500 And then here, I'll say color is blue. 91 00:06:45,230 --> 00:06:45,590 All right. 92 00:06:45,890 --> 00:06:54,830 So use hashtags for IDs and periods and the class name you can see now, I've specifically targeted 93 00:06:55,130 --> 00:06:55,850 that ID. 94 00:06:56,600 --> 00:07:00,650 And let's say we want to also have a specific target for below the div. 95 00:07:01,220 --> 00:07:03,630 I can give this an ID of two. 96 00:07:04,160 --> 00:07:05,600 Then I'll come back to the case. 97 00:07:07,080 --> 00:07:08,100 Say hashtag to. 98 00:07:09,300 --> 00:07:11,160 And let's give this a color green. 99 00:07:13,310 --> 00:07:20,120 OK, so I have above the div inside the div, below the div and second div, and even though these are 100 00:07:20,120 --> 00:07:25,490 all paragraph tags you can now see, I have a lot more flexibility in how I can style things. 101 00:07:25,850 --> 00:07:30,680 And let's imagine I wanted everything inside a div to have the color red. 102 00:07:31,040 --> 00:07:36,140 Well, then I can just put my paragraph tags inside the div so I can say also inside the div. 103 00:07:36,530 --> 00:07:41,120 And then if I wanted this to also have that effect, I can grab class again. 104 00:07:42,430 --> 00:07:45,310 Put it in here and now you can begin to see. 105 00:07:45,970 --> 00:07:52,510 Also in second, if you can begin to see how you can begin to organize containers in order to style 106 00:07:52,510 --> 00:07:53,470 only certain things. 107 00:07:53,980 --> 00:08:00,670 So the takeaway here is you use IEDs for a specific element and these should be unique. 108 00:08:00,670 --> 00:08:05,860 You should have two IEDs on the page that have the same name, even though it will technically still 109 00:08:05,860 --> 00:08:06,160 work. 110 00:08:06,370 --> 00:08:07,660 That's not really what they're meant for. 111 00:08:07,690 --> 00:08:11,800 They're just meant for unique identification of a specific element. 112 00:08:12,160 --> 00:08:15,280 If you do want something to be reused, you can use classes for that. 113 00:08:15,700 --> 00:08:18,040 Now, the classes need to be inside a div. 114 00:08:18,280 --> 00:08:19,360 No, not necessarily. 115 00:08:19,390 --> 00:08:21,640 You can have this be a class instead. 116 00:08:22,090 --> 00:08:28,780 So I could put this class attribute inside a paragraph as well, and it's going to work totally OK. 117 00:08:28,810 --> 00:08:31,870 So I can assign everything here with the class and notice. 118 00:08:31,870 --> 00:08:33,429 Now everything is read. 119 00:08:33,580 --> 00:08:37,600 And if I remove a class from something, you'll notice it turns black over here. 120 00:08:38,350 --> 00:08:43,419 So classes are OK to put in on a single element level. 121 00:08:43,690 --> 00:08:48,100 You'll typically see them inside a device because it just kind of works out that way that you get this 122 00:08:48,100 --> 00:08:48,970 nice little container. 123 00:08:49,210 --> 00:08:54,730 But you can then pass in styling codes, too, but it's totally up to you, and it depends on the situation. 124 00:08:55,330 --> 00:08:55,630 OK. 125 00:08:56,020 --> 00:08:58,660 So that's it for the idea of classes. 126 00:08:58,660 --> 00:09:02,890 And its main takeaway here is you can assign classes and IDs. 127 00:09:03,130 --> 00:09:08,800 Classes use a period in order for that selector to work IDs, use a hashtag in order for that selector 128 00:09:08,800 --> 00:09:09,130 to work. 129 00:09:09,700 --> 00:09:11,170 Thanks, and I'll see you at the next lecture.