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JavaScript: Enhancing the DOM
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Detecting data attributes


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JavaScript: Enhancing the DOM

with Ray Villalobos

Video: Detecting data attributes

In an HTML document, a developer can type in any attributes, even if they don't necessarily exist and pretend they're valid HTML. The browsers usually ignore them, but validaters will flag these as not being normal HTML. This is the HTML for the document we've been working with. And if I want to, I can add a coolness attribute here and set it to whatever I want. Now, the browser is probably going to ignore this attribute and not do anything with it, but if I try to validate my document. I want to copy this and I'll switch over to the WC3 validater.
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  1. 2m 36s
    1. Welcome
      59s
    2. What you should know before watching this course
      50s
    3. Using the exercise files
      47s
  2. 24m 33s
    1. What is the Document Object Model (DOM)?
      3m 2s
    2. Navigating the DOM with developer tools
      8m 10s
    3. Testing JavaScript commands with the console
      5m 50s
    4. Communicating with the console through JavaScript
      7m 31s
  3. 31m 9s
    1. Selecting elements with getElementById
      4m 10s
    2. Choosing elements by HTML tag
      3m 20s
    3. Isolating elements by class name
      3m 12s
    4. Querying CSS to select elements
      4m 54s
    5. Working with named form elements
      3m 39s
    6. Understanding nodeType, nodeName, and nodeValue
      4m 30s
    7. Traversing up and down DOM nodes
      4m 40s
    8. Targeting node elements
      2m 44s
  4. 22m 25s
    1. Changing HTML attributes
      5m 25s
    2. Working with restricted attributes
      2m 49s
    3. Detecting data attributes
      3m 29s
    4. Controlling classes with the HTML5 classList
      3m 21s
    5. Targeting the attributes property
      1m 24s
    6. Using text content modifiers
      3m 42s
    7. Modifying elements as text
      2m 15s
  5. 14m 57s
    1. Creating and appending nodes
      4m 27s
    2. Controlling node insertions with insertBefore
      3m 17s
    3. Cloning and removing nodes
      4m 41s
    4. Replacing existing nodes
      2m 32s
  6. 26m 14s
    1. What we'll build
      2m 16s
    2. Adding a bubbling event listener
      4m 11s
    3. Creating and styling an overlay with JavaScript
      4m 39s
    4. Adding an image
      3m 48s
    5. Resizing images in the DOM
      2m 59s
    6. Centering an image
      2m 36s
    7. Handling clicks
      1m 29s
    8. Adjusting for scrolling
      1m 36s
    9. Detecting and adjusting for a window resize
      2m 40s
  7. 1m 49s
    1. Next steps
      1m 49s

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JavaScript: Enhancing the DOM
2h 3m Intermediate Jun 10, 2013

Viewers: in countries Watching now:

The Document Object Model (DOM) is at the core of every HTML page. In order to develop dynamic HTML pages, a front-end developer needs to understand how JavaScript connects to and controls the DOM, allowing you to create, modify, delete, and edit existing page content. This course focuses on helping you understand the DOM elements, and shows the different ways JavaScript gives you access to them and makes it easier to work with the DOM. Author Ray Villalobos covers navigating the DOM, selecting elements, modifying HTML attributes, editing nodes, and much more.

Topics include:
  • What is the DOM?
  • Choosing and isolating elements
  • Traversing up and down DOM nodes
  • Changing HTML attributes
  • Modifying elements as text
  • Creating and appending nodes
  • Cloning and removing nodes
  • Adding a bubbling event listener
  • Adding and resizing images
  • Handling clicks
Subjects:
Developer Web Web Design Web Development
Software:
HTML JavaScript
Author:
Ray Villalobos

Detecting data attributes

In an HTML document, a developer can type in any attributes, even if they don't necessarily exist and pretend they're valid HTML. The browsers usually ignore them, but validaters will flag these as not being normal HTML. This is the HTML for the document we've been working with. And if I want to, I can add a coolness attribute here and set it to whatever I want. Now, the browser is probably going to ignore this attribute and not do anything with it, but if I try to validate my document. I want to copy this and I'll switch over to the WC3 validater.

And I'll click on the Validate By Direct Input tab, and paste my code right there. And I'll hit the Check button, you could see that it's telling me that there's at least one error there. Let me scroll all the way to the bottom, and notice that it says attribute coolness not allowed on element image at this point. It really means that it doesn't know anything about this new attribute that I just invented. So, thankfully HTML5 provides a way of adding special data attributes, so that if you want to you can create your own while remaining valid HTML. You simply create an attribute with a name that starts with data, you add a hyphen then any other name that you want. So, for example, you can use an attribute called data-coolness, and neither the browser or the validators will have a problem with it. If you want to access it, the node.dataset property lets you get to these using JavaScript.

So, let's take a look at how that works. So, for example, on this page, I want to get to one of these images right here, because I've added a special attribute called data task to some of these speakers. So, I'm going to get to the console. And I'll hit this magnifying glass and click on, I'll click on this second image. I think that has the right attribute. Notice that that one has a data task of speaker. And that's really the one I want to target. So, what I'll do is I'll create a variable.

And this time I want to choose queryselectorall because I want to get all of the images. And I'm going to hit Return, type in myNode and hit Enter. You can see a list of every one of the presenters. Notice that some of them have a data task attribute. So, if I want to get the value of that attribute, first I need to make sure that I have the right target. So, if I say myNode and I want to get the second element, which is element one, because I raised our 0 indexed and that gets me to that element. So, I can say something like myNode1.dataset, and use the name after the hyphen, right here, so just call it task.

And it let's me know what the value of that is. So, if I want to set that, all I have to do is give it a name right here. I'll call this presenter, presenter. And that modifies the value of that node. So I can set it back, just as easliy. Now this is really handy in accessing elements in projects created with frameworks like jQuery mobile, because it heavily uses the data attribute to set things. However, it does have spotty support in browsers.

If you really want to be safe, you should probably use the set and get attribute functions for data attributes. Although this is a really handy function, I would probably stay away from it at this time, because of lack of support in JavaScript. Still if you're trying to make your own tags, you should probably use the data attribute itself, it's a really good idea.

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