Python for Entrepreneurs Transcripts
Chapter: Web design foundations
Lecture: Browser Dev Tools

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0:01 We played a little bit with the dev tools in the browser
0:04 now it's time to actually focus on them a little more deeply.
0:07 Now, notice in this particular example I'm using Firefox,
0:10 the other browser I use all the time is Chrome, and almost every browser,
0:15 every major browser has some form of dev tools in it
0:20 and they are quite similar in a lot of ways
0:22 but they all have some unique thing to them,
0:24 what you see here might not be exactly what you have in Chrome and so on,
0:27 but they are all really good and the idea is what is more important here is
0:31 you have these tools available to help you,
0:33 let's use some of those tools on this page.
0:36 So we come over here, there is several ways you can get to it,
0:39 you've got tools, developer tools,
0:40 I find this often easiest to just right-click and say "inspect element"
0:43 and that will pull up the tools,
0:44 right now I have them in this separate page here
0:46 and you can see, let's scroll through this page for a minute here.
0:50 In Firefox they have this cool thing where you can go into inspector mode
0:55 and then click this and say I want to know what that is, or this or this,
0:59 and click that, and then you come back,
1:02 you can see it's selected the various things and also as you move around here,
1:05 so you can always move around here
1:07 but sometimes you are like "I want to know what is that",
1:11 and so you select it and there it is,
1:13 now, you can even do things like you can change the content,
1:17 so this says 7.2 hours, maybe you guys think that's too long,
1:20 so you come over here make that 5 hours and change it.
1:24 Or you could change this hyperlink or you can go and edit this,
1:27 if you want to edit a big block, you can actually come down here and say edit,
1:30 and you actually get in here and like rewrite the HTML when you click out,
1:33 it regenerates whatever it is going to be on the DOM there.
1:36 All right, that's cool, let's go back to this subtext thing.
1:39 You can see all the CSS styles over here, like you can see the subtext here,
1:43 I'll hover it here I'll show you exactly where it is,
1:45 see how it's centered in the page,
1:47 and that's because we have top-courses.pitch and it has "text-align: center".
1:51 But we can toggle these on and off, I can change it here if I want the color to be yellow,
1:56 I can change it here and notice, it's just this little tiny bit there.
2:01 Oh here we go, we are messing with this one down here,
2:03 let's move this a little to the side here.
2:06 So when I was tweaking with it, it ended up over here,
2:08 so we can do things like change the color, turn it on and off, and so on,
2:12 and this lets you explore the design parts of this page like, let's go up
2:17 and we can find the pictures, so like here is the image
2:20 and we can say you know what, what if I just want the width of this image
2:24 or what it would look like if it's a 150 pixels.
2:26 And you can just set it and tweak it here. So this is really cool for the design.
2:29 We also have a console, which is basically just a JavaScript console
2:33 and so you can do anything that you would normally do,
2:35 like if I want to find all the images, on the page, I can give it the CSS selector,
2:39 and you can see it came back with five images,
2:42 we could even do a little function on it,
2:45 we could log out what we have in on images.
2:47 If I run this, you can see actually those are all the images on the page,
2:50 whatever JavaScript you want to run, you can do this here.
2:52 This is also important for showing you errors,
2:54 like if there is a JavaScript error on the page or if there is like a 404 or 500,
2:59 you'll often see them show up down here as well; all right, so this is cool.
3:02 And like here you can see the various things we have it turned on for, right,
3:06 we could show errors and warnings for JavaScript or less, yeah.
3:10 Pretty remarkable that actually the print in the console still lets you go back
3:14 and select these in the DOM, I haven't realized that before, this is pretty amazing.
3:19 Ok, we can go to the style editor and do some styles here
3:21 and kind of tweak it in a more permanent way that may poke in at the DOM,
3:25 you can do profiling, we are not going to do that,
3:27 you can check out what's going on at the network,
3:28 this is pretty interesting, so let me change the size here a little,
3:34 like this, so we can still see it going,
3:35 let's say I only want to pay attention to just the document for now,
3:39 so just this, we have the courses/all and you can actually see the response time,
3:43 the server is pretty far away from me, it's on the East Coast of the US,
3:47 I figure that is kind of half way between the US and Europe
3:50 and it makes everyone more or less happy,
3:52 but I'm on the West Coast, so like the ping time is a 100 milliseconds,
3:55 just to get there, so this is pretty good response time,
3:58 we can come down here and view like a particular page, 140 milliseconds.
4:02 We can also see things about the CSS, and we can see things about JavaScript,
4:06 we can see things about images.
4:08 One thing to notice, we talked about the caching and cache busting,
4:11 so notice this here bootstrap.min, that's a cache id, font-awesome...cache_id,
4:15 all these things, here notice, out of the cache, out of the cache,
4:20 so there is quite a few requests going back to this page,
4:23 get me these images, get me these style sheets, get me these fonts,
4:26 but we've only made one request to the server,
4:29 and that's for the main content and everything else is cached, so that's really cool.
4:33 Few more things we can look at, we can jump between various pages
4:37 if you have like frames there, if we click this,
4:41 you can actually put this into like a responsive design mode
4:44 so here I can like make sure that my little drop-downs are working good,
4:49 you can set the size to be various things
4:51 like you want to test what it looks like if say it's on a tablet,
4:54 or if I want to test what it looks like if it's in various ways,
4:56 and even go into like a touch mode here.
4:59 I want to show you another one that looks kind of flashy
5:02 and you might be like "oh that's kind of a cool gimmick",
5:06 but it can actually be pretty helpful in helping you understand
5:09 how pages are laid out, especially if you want to go look at someone else's design
5:12 and say "how do they do that?". It's this thing called Tilt 3D
5:15 so let's go over here to tools, web developer and I've installed it,
5:18 it's add-on, I'll show you where it is in a moment and click this,
5:22 and it gives us a 3 dimensional stacked view of the web page,
5:25 you can kind of see like it looks like that standing out on top of that
5:29 which is standing on top of this, it gives you a view over here on the left,
5:32 that's pretty cool, the real thing is that's cool as when you grab it in the middle
5:36 and you rotate it like this, and you turn it around like so.
5:40 And say "I want to look over on this side, let's look over here,
5:45 and I want to know like what is this thing that contains both
5:50 the image and this logo up here."
5:54 So I can click on this and actually double click it and it will pull this up
5:57 and it will say that's the navbar brand top nav image, here is the actual content.
6:02 Or you can say you know, what is this thing down here, containing this,
6:07 oh I see, that's a form control, which is input,
6:10 you can see this is your email address.
6:12 All right, so you can get actually a pretty interesting view
6:15 by looking around and going "OK, I want to try to understand
6:19 what are the building blocks of this piece,
6:21 how do they put that together", and you could do that pretty well
6:24 with this Tilt 3D thing, and you get it for Firefox over here at addon/tilt.
6:31 One of the things to notice, that's pretty cool,
6:33 like if I come over here back to this Tilt thing, notice when I pull it up,
6:36 it has, it was looking like this before, when I pull it up,
6:39 you can actually go up here and pull out other things on it as well,
6:42 so I can come over here and say "show me just the HTML"
6:44 or "show me the CSS that applies to it",
6:47 or "show me the attributes that are set on it",
6:50 so this is pretty cool for exploring things, so I recommend you check it out.