var x = document.createElement('P')

• Opera < 9 and NetFront also support ('<P>').

var x = document.createTextNode('text')

Create a text node with content text and temporarily place it in x, which is later inserted into the document.

var x = document.getElementById('test')

Take the element with id="test" (wherever it is in the document) and put it in x.

If there is more than one element with id="test", the method selects the first in the document. All others are ignored.

• Opera < 9 also returns the element with name="test".

document.getElementsByClassName('test')
document.getElementsByClassName('test test2')

The first expression returns a nodeList with all elements that have a class value that contains "test". The second one returns a nodeList will all elements that have a class value that contains both "test" and "test2" (in any order).

var x = document.getElementsByTagName('P')

Make x into a nodeList of all P's in the document, so x[1] is the second P etc.

var x = y.getElementsByTagName('P')

Gets all paragraphs that are descendants of node y.

document.querySelectorAll('.testClass')
document.querySelectorAll('.testClass + p')

Returns a nodeList with all elements that have a class value that contains "testClass"; or a nodeList with all paragraphs directly following such an element.

Essentially, this method allows you to use CSS syntax to retrieve elements.

x.nodeName

The name of node x. The correct names are:

x.nodeType

The type of node x. The correct types are:

x.nodeValue

Get the value of node x

x.nodeValue = 'Test'

Set the value of node x

• Opera 8, S60 WebKit on Samsung, NetFront on SE, and Blackberry return // for a comment.

x.tagName

Get the tag name of node x. Correct values are:

My advice is not to use tagName at all.
nodeName contains all functionalities of tagName, plus a few more. Therefore nodeName is always the better choice.

x.childNodes[1]

Get the second child node of node x.

The childNodes nodeList consists of all child nodes of the element, including (empty) text nodes and comment nodes.

• Blackberry, NetFront, Opera 8.00, and S60 WebKit on Samsung do not count empty text nodes.

x.children[1]

Get the second element child node of node x.

Where childNodes holds all child nodes, children only holds those that are element nodes (HTML tags).

x.firstChild

Get the first child node of node x.

x.lastChild

Get the last child of node x.

x.nextSibling

Get the next child of the parent of x.

x.parentNode

Get the parent node of x.

x.previousSibling

Get the previous child of the parent of x.

x.sourceIndex

Get the sourceIndex of element x. This is also the index number for the element in the document.getElementsByTagName('*') array.

x.appendChild(y)

Make node y the last child of node x.

If you append a node that's somewhere else in the document, it moves to the new position.

x = y.cloneNode(true | false)

Make node x a copy of node y. If the argument is true, the entire tree below y is copied, if it's false only the root node y is copied.

Later you insert the clone into the document.

x.insertBefore(y,z)

Insert node y as a child of node x just before node z.

x.removeChild(y)

Remove child y of node x.

x.replaceChild(y,z)

Replace node z, a child of node x, by node y.

x.appendData(' some extra text')

Appends the string some extra text to x, which must be a text node.

x.data

The content of x, which must be a text node. The same as x.nodeValue.

Can also be set:

x.data = 'The new text'

x.deleteData(4,3)

Delete some data from x, which must be a text node, starting at the fifth character and deleting three characters. Second argument is required.

x.insertData(4,' and now for some extra text ')

Insert the string and now for some extra text after the fourth character into x, which must be a text node.

x.normalize()

All child nodes of node x that are text nodes and have other text nodes as siblings, are merged. This is in fact the reverse of splitText: text nodes that were split, come together again.

x.replaceData(4,3,' and for some new text ')

Replace three characters, beginning at the fifth one, of node x, which must be a text node, by the string and for some new text.

x.splitText(5)

Split the text node x at the 6th character. x now contains the first part (char. 0-5), while a new node is created (and becomes x.nextSibling) which contains the second part (char. 6-end) of the orginial text.

x.substringData(4,3)

Takes a substring of x, which must be a text node, starting at the fifth character and with a length of three characters. Thus it's the same as the old substr() method of strings.

This read-only property is useful if you want to get the entire text at a certain point and don’t want to be bothered by borders between text nodes.

x.attributes[1]

This array consists of all defined attributes in the source code order .

Do yourself a favour and don't use the indexed attributes array.

x.attributes['align']

Get the align attribute object of node x. If the node has no align attribute, it returns undefined (except in IE, where it returns an attribute object that has no value.)

After years in the wilderness attribute[key] is slowly approaching a workable situation. I used to advice you not to use it; but by now you can try it if you like.

x.getAttribute('align')

Gives the value of the align attribute of node x. Upper case attribute names are also allowed.

x.getAttributeNode('align')

Get the attribute object align of node x. This is an object, not a value.

x.hasAttribute('align')

Returns true when node x has an align attribute, false when it hasn't.

x.hasAttributes()

Returns true when node x has attributes, false when it hasn't.

x.name

The name of attribute node x.

x.removeAttribute('align')

Remove the align attribute from node x.

• Opera doesn't remove event handlers.

x.removeAttributeNode(x.attributes['align'])
x.removeAttributeNode(x.attributes[1])
x.removeAttributeNode(x.getAttributeNode('align'))

Removes the attribute node. There is little difference with removeAttribute(), except in the argument.

• Opera doesn't remove event handlers.

x.setAttribute('align','right')

Set the align attribute of node x to right. The name and value are both strings.

x.value

The value of attribute x.

x.compareDocumentPosition(y)

Compares the document (DOM) position of element y to that of element x The method returns a bitmask:

• 1: Position disconnected
• 2: Precedes
• 4: Follows
• 8: Contains
• 16: Is contained by

All relevant numbers are added, and this sum is returned. So if y follows (4) and is contained by (16) x, the method returns 20.

x.contains(y)

If node y is a descendant of node x, the method returns true, else false.

See this blog post for a Firefox workaround. (And yes, Firefox’s constant refusal to implement this very useful method is becoming extremely annoying.)

• S60 WebKit always returns true, except when you ask if an element contains itself (should return true, oddly enough, but S60 WebKit returns false.

x = document.createDocumentFragment();
x.[fill with nodes];
document.[somewhere].appendChild(x);

Create a fragment, add a lot of nodes to it, and then insert it into the document. Note that the fragment itself is not inserted, only its child nodes.

• Blackberry doesn’t run the second test (where nodes are removed from the document to the fragment) correctly: it doesn’t insert the fragment, although the nodes are removed.

document.documentElement

Represents the root element of the XML document. In any HTML document, the <html> element is of course the root element.

var x = document.getElementsByName('test')

Create a nodeList with all elements that have name="test". It should ignore elements with id="test"

On my test page the <p>, <input>, <img> and <ppk> tags have this name, while there's also a paragraph with id="test". Ideally, all browsers should get the first four elements and ignore the fifth one.

• Opera 9 counts the <div> with id="test"
• Opera 8 does the same, and doesn’t return the <p> and <ppk>.
• NetFront SE C510 does not return the <ppk> tag.

x.hasChildNodes()

Returns true when node x has child nodes; false when it hasn't.

document.getElementsByTagName('P').item(0)

The same as document.getElementsByTagName('P')[0].

The item() method is meant for other programming languages where nodeLists like those returned by getElementsByTagName are not conveniently accessible as if they were arrays.

You don't need item() at all in JavaScript.

x.ownerDocument

Refers to the document object that 'owns' node x. This is the document node.