diff options
Diffstat (limited to '')
-rw-r--r-- | browser/extensions/webcompat/lib/messaging_helper.js | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/browser/extensions/webcompat/lib/messaging_helper.js b/browser/extensions/webcompat/lib/messaging_helper.js new file mode 100644 index 0000000000..d978ed384f --- /dev/null +++ b/browser/extensions/webcompat/lib/messaging_helper.js @@ -0,0 +1,36 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +"use strict"; + +/* globals browser */ + +// By default, only the first handler for browser.runtime.onMessage which +// returns a value will get to return one. As such, we need to let them all +// receive the message, and all have a chance to return a response (with the +// first non-undefined result being the one that is ultimately returned). +// This way, about:compat and the shims library can both get a chance to +// process a message, and just return undefined if they wish to ignore it. + +const onMessageFromTab = (function () { + const handlers = new Set(); + + browser.runtime.onMessage.addListener((msg, sender) => { + const promises = [...handlers.values()].map(fn => fn(msg, sender)); + return Promise.allSettled(promises).then(results => { + for (const { reason, value } of results) { + if (reason) { + console.error(reason); + } else if (value !== undefined) { + return value; + } + } + return undefined; + }); + }); + + return function (handler) { + handlers.add(handler); + }; +})(); |