forked from mirrors/gecko-dev
36 lines
1.2 KiB
JavaScript
36 lines
1.2 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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"use strict";
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/* globals browser */
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// By default, only the first handler for browser.runtime.onMessage which
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// returns a value will get to return one. As such, we need to let them all
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// receive the message, and all have a chance to return a response (with the
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// first non-undefined result being the one that is ultimately returned).
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// This way, about:compat and the shims library can both get a chance to
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// process a message, and just return undefined if they wish to ignore it.
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const onMessageFromTab = (function() {
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const handlers = new Set();
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browser.runtime.onMessage.addListener((msg, sender) => {
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const promises = [...handlers.values()].map(fn => fn(msg, sender));
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return Promise.allSettled(promises).then(results => {
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for (const { reason, value } of results) {
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if (reason) {
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console.error(reason);
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} else if (value !== undefined) {
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return value;
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}
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}
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return undefined;
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});
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});
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return function(handler) {
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handlers.add(handler);
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};
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})();
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