gecko-dev/toolkit/modules/PromiseMessage.jsm

37 lines
1014 B
JavaScript

/* 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";
this.EXPORTED_SYMBOLS = ["PromiseMessage"];
var msgId = 0;
var PromiseMessage = {
send(messageManager, name, data = {}) {
let id = msgId++;
// Make a copy of data so that the caller doesn't see us setting 'id'.
let dataCopy = {};
for (let prop in data) {
dataCopy[prop] = data[prop];
}
dataCopy.id = id;
// Send the message.
messageManager.sendAsyncMessage(name, dataCopy);
// Return a promise that resolves when we get a reply (a message of the same name).
return new Promise(resolve => {
messageManager.addMessageListener(name, function listener(reply) {
if (reply.data.id !== id) {
return;
}
messageManager.removeMessageListener(name, listener);
resolve(reply);
});
});
}
};