From: FAQ server on
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FAQ Topic - What is a host object?
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A host object is any object supplied by the host environment to
complete the execution environment of ECMAScript.

A host object is not part of the ECMAScript implementation, but is
exposed to the ECMAScript implementation.

A host object may be implemented as a native ECMAScript object, however
this is not required. For example, Internet Explorer implements many
scriptable DOM objects as ActiveX Objects, often resulting in unexpected errors.

Availability and behavior of a host object depends on the host environment.

For example, in a browser, `XMLHttpRequest` might be available, with or
without standard or proprietary features or events. Windows Script Host object model
has the `WScript` object available.

For information on a particular host object, consult the pertinent
documentation available for the implementation(s). For web browsers,
this usually includes the w3c specifications as well as documentation
for that browser.
See also:

<URL: http://jibbering.com/faq/notes/code-guidelines/#hostObjects>
<URL: http://peter.michaux.ca/articles/feature-detection-state-of-the-art-browser-scripting>


The complete comp.lang.javascript FAQ is at
http://jibbering.com/faq/

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