Google Chrome扩展程序中的同步通话

Question

我正在使用Google Chrome扩展程序，该扩展程序必须阻止/重定向某些传出请求。为此，我使用chrome.webRequest.onBeforeRequest监听器。 要决定是否阻止请求，我需要一些有关标签请求的信息。我可以使用chrome.tabs.get(integer tabId, function callback)来获取它，但回调是异步的，这意味着可以在从onBeforeRequest侦听器返回值之后调用它。

chrome.webRequest.onBeforeRequest.addListener(function(details){
 chrome.tabs.get(details.tabId, function(tab){
  // get info from tab
 }); 
 // based on info from tab return redirect or not
}), {
 urls: ["<all_urls>"],
 types: ["main_frame"]
}, ["blocking"]);

有没有办法同步通话？或许还有其他一些选择。

Answer 1

Another answer on Stack Overflow建议跟踪侦听器功能的外部标签，这样可以完全避免此问题。

示例代码：

/* 
 * --------------------------------------------------
 * Keep list of tabs outside of request callback
 * --------------------------------------------------
 */
var tabs = {};

// Get all existing tabs
chrome.tabs.query({}, function(results) {
    results.forEach(function(tab) {
        tabs[tab.id] = tab;
    });
});

// Create tab event listeners
function onUpdatedListener(tabId, changeInfo, tab) {
    tabs[tab.id] = tab;
}
function onRemovedListener(tabId) {
    delete tabs[tabId];
}

// Subscribe to tab events
chrome.tabs.onUpdated.addListener(onUpdatedListener);
chrome.tabs.onRemoved.addListener(onRemovedListener);

/* 
 * --------------------------------------------------
 * Request callback
 * --------------------------------------------------
 */
// Create request event listener
function onBeforeRequestListener(details) {
    // *** Remember that tabId can be set to -1 ***
    var tab = tabs[details.tabId];

    // Respond to tab information
}

// Subscribe to request event
chrome.webRequest.onBeforeRequest.addListener(onBeforeRequestListener, {
    urls: ["<all_urls>"],
    types: ["main_frame"]
}, ["blocking"]);

Answer 2

chrome.runtime.onMessage.addListener((message, rawSender, sendResponse) => {

        // here, you can call sendResponse method in any where asynchronous.

        return true;    // 这是重点，it's important
    }
);

// it also fit chrome.webRequest.onBeforeRequest.addListener