зеркало из https://github.com/mozilla/gecko-dev.git
44 строки
1.2 KiB
JavaScript
44 строки
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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const {Cu, CC} = require("chrome");
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const promise = require("promise");
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const {Services} = Cu.import("resource://gre/modules/Services.jsm");
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const XMLHttpRequest = CC("@mozilla.org/xmlextras/xmlhttprequest;1");
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// Downloads and caches a JSON file from a URL given by the pref.
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exports.getJSON = function (prefName, bypassCache) {
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if (!bypassCache) {
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try {
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let str = Services.prefs.getCharPref(prefName + "_cache");
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let json = JSON.parse(str);
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return promise.resolve(json);
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} catch(e) {/* no pref or invalid json. Let's continue */}
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}
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let deferred = promise.defer();
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let xhr = new XMLHttpRequest();
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xhr.onload = () => {
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let json;
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try {
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json = JSON.parse(xhr.responseText);
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} catch(e) {
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return deferred.reject("Invalid JSON");
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}
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Services.prefs.setCharPref(prefName + "_cache", xhr.responseText);
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deferred.resolve(json);
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}
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xhr.onerror = (e) => {
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deferred.reject("Network error");
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}
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xhr.open("get", Services.prefs.getCharPref(prefName));
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xhr.send();
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return deferred.promise;
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}
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