This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

js-ctypes allows application and extension code to call back and forth to native code written in C. C++ support is possible through vtable pointers see Using COM from js-ctypes. For a discussion on extended C++ support see bugĀ 505907. Other work made possible by js-ctypes is JNI, this is elaborated on in theĀ JNI.jsm section and not the js-ctypes section due to the JSM abstracting away all of the js-ctypes. Unlike binary XPCOM components, it allows developers to ship a single binary for use with multiple versions of Firefox.

Note: js-ctypes is only available from chrome code; that is, ctypes is not available to websites, only application and extension code.


If you are brand new to js-ctypes, and have no idea about it, the pages you should read first is - followed by Standard OS Libraries.

Using JS-Ctypes
JS-ctypes Reference
A reference guide to the js-ctypes API.

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Add to iPhoto
A Firefox extension that uses js-ctypes to call Carbon and Core Foundation framework routines on Mac OS X to implement an "Add image to iPhoto" feature in Firefox.
Using C structs and pointers
Using COM from js-ctypes
Using Objective-C from js-ctypes
Github :: ochameau / jscpptypes
A mangling library to use C++ from js-ctypes