Navigating The Family Tree - DHTML

It's the bane of Web developers everywhere - conflicting standards, browser incompatibilities, and code that changes every time a new browser version hits the Web. But fear not - charging in on a white steed comes a heroic knight, clad in the attire of the new W3C DOM and armed with the tools to make this nightmare end forever. Read on to find out how the new DOM finally brings some standards to the decidedly non-standard world of the Web.

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By: Vikram Vaswani, (c) Melonfire

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April 09, 2001

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TOOLS YOU CAN USE

In addition to the various childNodes[], the DOM also offers a number ofother objects/properties which can simplify navigation between documentelements.

firstChild - a reference to the first child node in the collection

lastChild - a reference to the last child node in the collection

parentNode - a reference to the node one level up in the tree

nextSibling - a reference to the next node in the current collection

previousSibling - a reference to the previous node in the current collection

And so, with reference to the example above, I could use any of thealternative routes below to navigate to the <div> tag.


document.childNodes[0].childNodes[1].firstChild
document.childNodes[0].firstChild.nextSibling.firstChild
document.childNodes[0].childNodes[1].firstChild.firstChild.parentNode

Each child in the tree can be either an HTML tag or a "text node". Thisbrings up an important point - blank spaces and carriage returns betweenthe various tags can affect the document tree structure, creating textnodes in the tree structure and causing much gnashing of teeth as youadjust your code to the new tree.

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