MDN’s new design is in Beta! A sneak peek: https://blog.mozilla.org/opendesign/mdns-new-design-beta/

Add-ons using the techniques described in this document are considered a legacy technology in Firefox. Don't use these techniques to develop new add-ons. Use WebExtensions instead. If you maintain an add-on which uses the techniques described here, consider migrating it to use WebExtensions.

From Firefox 53 onwards, no new legacy add-ons will be accepted on addons.mozilla.org (AMO).

From Firefox 57 onwards, WebExtensions will be the only supported extension type, and Firefox will not load other types.

Even before Firefox 57, changes coming up in the Firefox platform will break many legacy extensions. These changes include multiprocess Firefox (e10s), sandboxing, and multiple content processes. Legacy extensions that are affected by these changes should migrate to WebExtensions if they can. See the "Compatibility Milestones" document for more.

A wiki page containing resources, migration paths, office hours, and more, is available to help developers transition to the new technologies.

Some simple code to turn a JavaScript module into non-Mozilla-specific code (e.g., if porting to the browser). The use of eval() will probably not be of concern because it is only being used on the EXPORTED_SYMBOLS array which should not depend on user input.

function importModule (thatObj) {
    thatObj = thatObj || window;

    var EXPORTED_SYMBOLS = [
    // Put the symbols here
    ];

    // Your code here...

    // At the end of your code: (assuming neither 'i' nor 'thatObj' is being exported!)
    for (var i=0; i < EXPORTED_SYMBOLS.length; i++) {thatObj[EXPORTED_SYMBOLS[i]] = eval(EXPORTED_SYMBOLS[i]);}
}

or for one-time-only usage of a module:

(function (thatObj) {
    thatObj = thatObj || window;

    var EXPORTED_SYMBOLS = [
    // Put the symbols here
    ];

    // Your code here...

    // At the end of your code: (assuming neither 'i' nor 'thatObj' is being exported!)
    for (var i=0; i < EXPORTED_SYMBOLS.length; i++) {thatObj[EXPORTED_SYMBOLS[i]] = eval(EXPORTED_SYMBOLS[i]);}
})(); // Can put an object argument here

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 Contributors to this page: bunnybooboo, wbamberg, Nickolay, Brettz9
 Last updated by: bunnybooboo,