JavaScript: The Definitive Guide, 6th Edition

Name

DOMTokenList — a set of space-separated tokens

Synopsis

A DOMTokenList is a parsed representation of a space-separated string of tokens, such as the className property of a Element. A DOMTokenList is, as its name implies, a list—it is an array-like object with a length property and you can index it to retrieve the individual tokens. But more importantly, it defines methods contains(), add(), remove(), and toggle() methods that allow you to treat it as a set of tokens. If you use a DOMTokenList as if it was a string, it evaluates to a space-separated string of tokens.

The HTML5 classList property of Element objects is a DOMTokenList, in browsers that support that property, and is the only DOMTokenList you are likely to use often. See also DOMSettableTokenList.

Properties

readonly unsigned long length

A DOMTokenList is an array-like object; this property specifies the number of unique tokens it contains.

Methods

void add(string token)

If the DOMTokenList does not already contain token, add it at the end of the list.

boolean contains(string token)

Returns true if the DOMTokenList contains token, or false otherwise.

string item(unsigned long index)

Return the token at the specified index or null if index is out of bounds. You can also index the DOMTokenList directly instead of calling this method.

void remove(string token)

If this DOMTokenList contains token, remove it. Otherwise, do nothing.

boolean toggle(string token)

If the DOMTokenList contains token, remove it. Otherwise add it.