如何从异步函数设置全局变量

Question

我坚持这个异步功能问题。我需要设置一个全局变量，其中包含我从回调函数获得的数据。我怎么能这样做？

var soundId;

soundcheck(soundId, function (num){getSound(soundId, num)});
//callback 
function getSound (soundId, result) {
var res = result;
if (!soundId) {
    soundId = res;
    }
    console.log(soundId);
};


function soundcheck(soundId, callback) {
    var lpid = $("a#entered_user_link").attr('href').substring(6);
        chrome.extension.sendMessage({lpid: lpid}, function(response) {
        if (response.resp) {
            check = response.resp;
            callback(check);
        }
    });
};

// i need to put response in this variable to use it in future
console.log(soundId);

Answer 1

您可能希望保持简单，特别是不要遮蔽您的变量。

var soundId;

soundCheck(function(result) {
  if(result) { 
    soundId = result;
  };
});

var soundCheck = function(callback) {
  var lpid = $("a#entered_user_link").attr('href').substring(6);
  chrome.extension.sendMessage({lpid: lpid}, function(response) {
    callback(response.resp);
  });
};

毕竟没有理由传递soundId。