DHTML Utopia: Modern Web Design Using JavaScript & DOM by Stuart contributes to Stylish Scripting: SitePoint’s DHTML and CSS Blog. About The. Modern Web Design Using JavaScript & DOM. HTML Source Review. Now that using nice, valid HTML and CSS for layout have been well and truly cracked. I remember the first time I saw an image rollover on a web site, and being blown away by the sheer coolness of such a thing. Of course I.

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One of the important things the figure illustrates is that the text inside an element is not part of that element. Finally, the page also contains images: It does seem that there are quite a few “critical” bits, I know! Another step to CSS guru-hood is understanding exactly what each browser does wrong, and how you can work around those failings.

Processing happens as follows.

Pat J on the 01 Jul It describes the document content as a set of objects that a JavaScript program can see. To facilitate this, we must move our “hookup” code from the HTML to a separate script section: There is another useful feature; getElementsByTagName is defined on any node at all, not just the document.

This is an jacascript benefit of the new technique: The chtml statement says: As mentioned above, browsers rely on a standard that describes how validated HTML should be interpreted. All this sniffing relies on JavaScript’s runtime behavior.

Click to popup a larger image of this table. Image rollover scripts, in which an image is used as a link, shtml that image changes when the user mouses over it, are a mainstay of JavaScript programming on the Web.

DHTML Utopia; modern web design using JavaScript & DOM.

Missing implementations are relatively easy to deal with: This marches up the tree from the element supplied in the first argument to find the first enclosing tag whose name matches the second argument. We want to confirm that this link contains nothing but an img element, so we make use of a very handy property of JavaScript, called short-circuit evaluation.

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Not so here, as the text is kept refreshingly free of unending details about different browser implementations of DOM methods, instead simply guiding you in the right direction of code branching and feature testing so your code will work as well as possible in each browser.

While it can be a lot of work, many CSS bugs only become apparent with the complex use of this technology; most CSS is handled perfectly across platforms and browsers without the need for hacks or complex tests. The addListeners function uses another familiar technique; it iterates through all the links on the page and does something to them. A large subset of DHTML scripts work by setting on page load some event listeners that will be called as various elements in the browser fire events.

The code above is flawed: Failing thatwe attach the event listener directly to the element, as an event handler; this is required for IE5 on Macintosh.

This allows us to put browser objects in all scripts, and use them only when our detection code gets around to it: HTML that complies with these rules is said to be “valid. However, there are no standards to describe how invalid HTML should be interpreted; each browser maker has established their own rules to fill that gap.

Looking at the above code may make this clearer. This returns a copy of the node, including all its attributes ytopia all its children. If a match for the regular moderb is found in the string, it is replaced by the substitute string. Each browser fixes malformed content in a different way, which can generate such horrors as an element that is its own parent node.

Some users find this useful; others find it heartily annoying.

Stuart Langridge, DHTML Utopia Modern Web Design Using JavaScript & DOM – ebooksz

Mixing these technologies together can result in a humble stew or a grandiose buffet. We’ll review the code first, then see a demonstration before we get to the explanation. This feature of JavaScript – the ability to test whether a method exists – has been part of the language since its inception; thus, it is safe to use it on even the oldest JavaScript-supporting browsers.

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It would be possible, given our event-handling techniques above, to give them the choice. Think of it as though you were shooting a scene for a movie. The keypress event is nonstandard i. This is where things get a little complicated. This isn’t a good approach to use. The top-left corner of the big image should be in the top-left corner of the viewing area: The upshot of this exercise is that all the cells in the same column as the moused-over cell will have class hi ; the table row containing the cell will also have class hi.

Modern Web Design Using JavaScript & DOM

For a document thumbnail such as this, we can use the cursor to move around the document within the viewing area, so that we can read the content and see if it’s the document we want. No surprises there, so we grab the required DOM element:. Instead, the approach taken is to use one of fom getElementsBy Whatever methods to grab a particular part of the tree directly.

We’ll explore and fix! Vhtml the variable node points to the ul element of the DOM tree.

The first line above executes the first task. Unfortunately, the clientX and clientY properties of the event object are nowhere near as reliable. Perhaps more importantly, the DOM3 recommendation does not mention a keypress event. We then manipulate xhtml position of that background image so that it moves in accordance with the cursor.

When we mouse-over a thumbnail image, though, the display javascrupt that thumbnail changes to show the actual image to which it’s linked, as shown in Figure 4.