Question

我已经在一个承诺中包装了jsonp请求，并且我正在进行一系列API调用，一旦它们全部解决后我想进一步处理。

 var users = ["ESL_SC2", "OgamingSC2", "cretetion", "freecodecamp", "habathcx", "RobotCaleb", "noobs2ninjas", "twitchpresents"]

Promise.all(users.map(function(user){
    var url = "https://wind-bow.gomix.me/twitch-api/users/" + user;
    return jsonp(url);
})).then(function(arr){
    console.log(arr);
})

它返回一个PromiseValue未定义的Promise数组，这不允许我进一步处理这些值。

我的JSONP承诺包装器在这里：

 var count = 0;

var jsonp = function(url, options) {
    options = options || {};

    var prefix = options.prefix || '__jp';
    var param = options.param || 'callback';
    var timeout = options.timeout ? options.timeout : 15000;
    var target = document.getElementsByTagName('script')[0] || document.head;
    var script;
    var timer;
    var cleanup;
    var cancel;
    var promise;
    var noop = function() {};

    // Generate a unique id for the request.
    var id = prefix + (count++);

    cleanup = function() {
        // Remove the script tag.
        if (script && script.parentNode) {
            script.parentNode.removeChild(script);
        }

        window[id] = noop;

        if (timer) {
            clearTimeout(timer);
        }
    };

    promise = new Promise(function(resolve, reject) {
        if (timeout) {
            timer = setTimeout(function() {
                cleanup();
                reject(new Error('Timeout'));
            }, timeout);
        }

        window[id] = function(data) {
            cleanup();
            resolve(data);
        };

        // Add querystring component
        url += (~url.indexOf('?') ? '&' : '?') + param + '=' + encodeURIComponent(id);
        url = url.replace('?&', '?');

        // Create script.
        script = document.createElement('script');
        script.src = url;
        target.parentNode.insertBefore(script, target);

        cancel = function() {
            if (window[id]) {
                cleanup();
                reject(new Error('Canceled'));
            }
        };

    });

    return {
        promise: promise.then(function(data){
            var user = {
                name: data.name,
                logo: data.logo,
            };


           userData.push(user);
        }),
        cancel: cancel
    };
}

我可以在单个API调用中推送结果，但有没有办法从Promise.All访问值？

Answer 1

你不会从承诺中归还任何东西。试试这个：

promise: promise.then(function(data){
  var user = {
    name: data.name,
    logo: data.logo,
  };

  userData.push(user);

  return user; // <-- pass data further
}),

Promise.all返回undefined

1 个答案: