铬Stroge同步返回错误

Question

//Options 
 
var useProxy = false; 
 
var useIPDebugger = false; 
 
var useUserAgentT = false; 
 
var useBlockJS = false; 
 
var useBlockCSS = false; 
 

 
//Load Options 
 
chrome.storage.sync.get("useUserAgent", 
 
    function(val) { 
 
    alert(val.useUserAgent); //return True 
 
    useUserAgentT = val.useUserAgent; //marking 
 
    } 
 
); 
 
alert(useUserAgentT); //but return False

val.useUserAgent将返回true，但useUserAgentT = val.useUserAgent;和alert(useUserAgentT);都返回false：对于文件/

更多细节。

options.js

$(document).ready(function() { 
 
\t var isCheckedProxy = false; 
 
\t var isCheckedIPDebug = false; 
 
\t var isCheckedUserAgent = false; 
 
\t var isCheckedJS = false; 
 
\t var isCheckedCSS = false; 
 
\t $('#isCheckedProxy').on('change', function(){ 
 
\t \t if(this.checked) {isCheckedProxy = true; chrome.browserAction.setBadgeText({text: String("true")});} else {isCheckedProxy = false; chrome.browserAction.setBadgeText({text: String("false")});} 
 
\t \t save_options(); 
 
\t }); 
 
\t $('#isCheckedIPDebug').on('change', function(){ 
 
\t \t if(this.checked) {isCheckedIPDebug = true;} else {isCheckedIPDebug = false;} 
 
\t \t save_options(); 
 
\t }); 
 
\t $('#isCheckedUserAgent').on('change', function(){ 
 
\t \t if(this.checked) {isCheckedUserAgent = true;} else {isCheckedUserAgent = false;} 
 
\t \t save_options(); 
 
\t }); 
 
\t $('#isCheckedJS').on('change', function(){ 
 
\t \t if(this.checked) {isCheckedJS = true;} else {isCheckedJS = false;} 
 
\t \t save_options(); 
 
\t }); 
 
\t $('#isCheckedCSS').on('change', function(){ 
 
\t \t if(this.checked) {isCheckedCSS = true;} else {isCheckedCSS = false;} 
 
\t \t save_options(); 
 
\t }); 
 
\t //Kaydet 
 
\t function save_options() { 
 
\t \t chrome.storage.sync.set({ 
 
\t \t \t isCheckedProxy: isCheckedProxy, 
 
\t \t \t isCheckedIPDebug: isCheckedIPDebug, 
 
\t \t \t isCheckedUserAgent: isCheckedUserAgent, 
 
\t \t \t useUserAgent: isCheckedUserAgent, //this is useUserAgent setting. 
 
\t \t \t isCheckedJS: isCheckedJS, 
 
\t \t \t isCheckedCSS: isCheckedCSS 
 
\t \t }, function() { 
 
\t \t \t //alert("saved."); 
 
\t \t }); 
 
\t } 
 
\t //Yükle 
 
\t function restore_options() { 
 
\t \t chrome.storage.sync.get({ 
 
\t \t \t isCheckedProxy: isCheckedProxy, 
 
\t \t \t isCheckedIPDebug: isCheckedIPDebug, 
 
\t \t \t isCheckedUserAgent: isCheckedUserAgent, 
 
\t \t \t isCheckedJS: isCheckedJS, 
 
\t \t \t isCheckedCSS: isCheckedCSS 
 
\t \t }, function(items) { 
 
\t \t \t $('#isCheckedProxy').attr('checked', items.isCheckedProxy); 
 
\t \t \t isCheckedProxy = items.isCheckedProxy; 
 
\t \t \t if(items.isCheckedProxy == true) {chrome.browserAction.setBadgeText({text: String("true")});} else {chrome.browserAction.setBadgeText({text: String("false")});} 
 
\t \t \t $('#isCheckedIPDebug').attr('checked', items.isCheckedIPDebug); 
 
\t \t \t isCheckedIPDebug = items.isCheckedIPDebug; 
 
\t \t \t $('#isCheckedUserAgent').attr('checked', items.isCheckedUserAgent); 
 
\t \t \t isCheckedUserAgent = items.isCheckedUserAgent; 
 
\t \t \t $('#isCheckedJS').attr('checked', items.isCheckedJS); 
 
\t \t \t isCheckedJS = items.isCheckedJS; 
 
\t \t \t $('#isCheckedCSS').attr('checked', items.isCheckedCSS); 
 
\t \t \t isCheckedCSS = items.isCheckedCSS; 
 
\t \t }); 
 
\t } 
 
\t restore_options(); 
 
});

background.js

//Options 
 
var useProxy = false; 
 
var useIPDebugger = false; 
 
var useUserAgentT = false; 
 
var useBlockJS = false; 
 
var useBlockCSS = false; 
 

 
//Load Options 
 
chrome.storage.sync.get("useUserAgent", 
 
    function(val) { 
 
    useUserAgentT = val.useUserAgent; 
 
\t //alert(val.useUserAgent); 
 
    } 
 
); 
 

 
alert(useUserAgentT); 
 

 
\t var items = ["Mozilla/5.0 (Windows NT 6.1; WOW64; rv:40.0) Gecko/20100101 Firefox/40.1", "Googlebot/2.1 (+http://www.google.com/bot.html)", "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/535.7 (KHTML, like Gecko) Comodo_Dragon/16.1.1.0 Chrome/16.0.912.63 Safari/535.7", "Mozilla/5.0 (compatible; BecomeBot/3.0; MSIE 6.0 compatible; +http://www.become.com/site_owners.html)", "Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20121202 Firefox/17.0 Iceweasel/17.0.1", "Mozilla/4.0 (compatible; MSIE 5.23; Macintosh; PPC) Escape 5.1.8", "Mozilla/5.0 (compatible; IBrowse 3.0; AmigaOS4.0)", "Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16"]; 
 
\t chrome.webRequest.onBeforeSendHeaders.addListener(function(details){ 
 
\t var headers = details.requestHeaders, 
 
\t blockingResponse = {}; 
 
\t for(var i = 0, l = headers.length; i < l; ++i) { 
 
\t \t if(headers[i].name == 'User-Agent') { 
 
\t \t headers[i].value = items[Math.floor(Math.random()*items.length)]; 
 
\t \t console.log(headers[i].value); 
 
\t \t break; 
 
\t \t } 
 
\t } 
 
\t blockingResponse.requestHeaders = headers; 
 
\t return blockingResponse; 
 
\t }, 
 
\t {urls: [ "<all_urls>" ]},['requestHeaders','blocking']); 
 
} 
 
//Set Status 
 
chrome.browserAction.setBadgeText({text: String("unknown")});

Answer 1

这是由于API的异步特性。 chrome.storage.sync.get()需要您的回拨（function (val) { /* ... */ }）并立即返回。回调在稍后的某个时刻被执行。所以，实际执行顺序是：

var useUserAgentT = false; 

/* ... */ 

alert(useUserAgentT); 

/* some time later in the callback */ 

useUserAgentT = val.useUserAgent.