foreach inside foreach，结果为空可能是因为异步调用

Question

变量 ntabs 最终是空的，我如何更改此代码（可能使用 Q 或异步库）以使其正常工作

var actions = [..];//array of objects
var ntabs = [];//arr where i put results

  actions.forEach(function(a) {
    chrome.tabs.query({url: a.url}, function(tabs) {
        tabs.forEach(function(tab) {
          var t = {
            id: tab.id,
            title: tab.title,
            url: tab.url,
            faviconUrl: tab.favIconUrl,
            actions: a.actions
          }
          ntabs.push(t);
        });
    });
  });

  console.log(ntabs);//result is empty

Answer 1

函数chrome.tabs.query是异步函数。您应该添加一个计数器，它将在最后一个查询完成时执行其余代码。

var actions = [{
  url: '
}, {
  url: 'chrome://extensions/?id=ehlnpfcjcalccnjondlokficpbkiefdk'
}];
var n = actions.length;
var ntabs = [];
actions.forEach(function(a) {
  chrome.tabs.query({
    url: a.url
  }, function(tabs) {
    tabs.forEach(function(tab) {
      var t = {
        id: tab.id,
        title: tab.title,
        url: tab.url,
        faviconUrl: tab.favIconUrl,
        actions: a.actions
      }
      ntabs.push(t);
    });
    if(--n === 0) onQuery();
  });
});

function onQuery() {
  console.log(ntabs);
}

foreach inside foreach，结果为空可能是因为异步调用

Foreach inside foreach, result is empty probably because of async call

javascript

asynchronous

google-chrome-extension

q

async.js