Document.implementation

The Document.implementation property returns a DOMImplementation object associated with the current document.

DOMImpObj = document.implementation;

var modName = "HTML";
var modVer = "2.0";
var conformTest = document.implementation.hasFeature( modName, modVer );

alert( "DOM " + modName + " " + modVer + " supported?: " + conformTest );

// alerts with: "DOM HTML 2.0 supported?: true" if DOM Level 2 HTML module is supported.

A list of module names (e.g., Core, HTML, XML, etc.) is available in the DOM Level 2 Conformance Section.

The W3C's DOM Level 1 Recommendation only specified the hasFeature method, which is one way to determine if a DOM module is supported by a browser (see example above and What does your user agent claim to support?). If available, other DOMImplementation methods provide services for controlling things outside of a single document. For example, the DOMImplementation interface includes a createDocumentType method with which DTDs can be created for one or more documents managed by the implementation.

• Starting with Gecko 19.0 (Firefox 19.0 / Thunderbird 19.0 / SeaMonkey 2.16) the hasFeature method will always return true.