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This is all fairly advanced stuff, so we need to confirm that the running browser supports all the features we need in order to make it work. We can shorten the code slightly to the following:. We use browser detection. Unfortunately, there is simply no better way around the problem in Safari. The last section of our code has little to do with browser detects, but, having spent all this time to get the right X and Y coordinates, it makes sense to understand how to use them.
You may recall from the previous chapter the technique of referring to a Function object without calling it. This site uses Webmention. We’re storing the dhrml of the larger image in custom attributes on the a element: Each browser manufacturer implemented its own proprietary means of providing scripting access to layers. Therefore, they will not run the code enclosed by the if statement; nor javasceipt they display an error. The first function does the work of converting the text.
The tasks are neatly divided. Some users find this useful; others find it heartily annoying. The thumbnail display implemented by the scrollImage example.
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.
If there are any children, their numbering starts at zero.
No surprises there, so we grab the required DOM element:. This makes your job as Website developer much easier. To see that document, you can ufopia display it in the browser window, or you can look at the HTML source. An event target is the thing at which an event is aimed — an element, essentially.
For example, all visible elements will fire a mouseover event when the mouse is moved over them. 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.
Key codes in the DOM are a standards mess! Moreover, if your site is required to last for any reasonable period of time, new browser versions will be released after your site, and your browser-sniffing code will be unable to account for them.
If the method does exist, we continue:. Matt Wilcox on the 15 Jun In our brave new world, we can add the extra name entry fields dynamically.
Just to make our lives as DHTML developers a little more complex, it also uses slightly different properties on the event object that it creates. An event listener is the thing that grabs the event when it appears, and responds to it. Our code will set up listeners only on browsers that do support those methods. But we can hook up the same function as an event listener on more than one element. Now you know how to get references to elements — the nodes in your HTML page.
Although this means more code, notice how it keeps the HTML content clean and simple. We walk through that array, applying the hi class to the cell in each row that has the same index as the moused-over cell.
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 matching DOM tree is shown in Figure 2.
This first part is related to DOM event handling, which is explained in the next chapter. Only entirely numeric properties, such as z-index which is set as node.
Lots of Websites contain photo galleries: The important part is that the information in the page is marked up in a way that describes what it is.
Symmetrically, the p node is the parent of the a node. Conceptually, the code works as follows: