What is the DOM?
The Document Object Model, or DOM, is an interface to allow programs and scripts to update content, structure, and style of documents dynamically. It is platform- and language-neutral. The DOM is not HTML nor is it JavaScript. It is something like the glue that binds them together.
DOM Level 0
The DOM level 0 is a mix of HTML functions that have not been formally specified that allow scripting languages to interact with Microsoft Internet Explorer 3.0 and Netscape Navigator 3.0. This basically means that if a DHTML page is compliant with DOM level 0 it should work reliably even in fairly old browsers.
The base structure of the DOM level 0 is the document master container. This refers to the entire document, and all elements within it. It is referenced as:
document
Because the DOM level 0 is very basic, it only allows the developer to manipulate items on the page that already have some level of interactivity, i.e. forms. It is possible to reference other items in a Web document, but most browsers don't support much interactivity with them at level 0.
Referencing Forms
There are three ways to reference a form control using DOM level 0:
by name or id
This is the easiest way to reference a form control, as you can clearly see in the XHTML which form you a referring to. For example, this form is named "form1":
<form name="form1" id="form1">...</form>
It would be referenced in the DOM as:
document.form1
Then if you wanted to reference an element within the form, you would name it as well:
document.form1.fname
references
<input type="text" name="fname" />
in the above form.
by number
Each form, and element within the form, is given a number in an array, starting with 0. They are numbered starting with the first
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