Javascript for Promises loop

Question

I have an array of urls like this

var urls = ["www.google.com", "www.yahoo.com"];

And I want to loop the urls and execute the asynchronous task inside the loop, and not go to the next element until the async task is complete. I know you can do this with promises, but I have problems with this. Here is what i have

var xmlReader = require('cloud/xmlreader.js');

function readResponse_async(xlmString) {
    var promise = new Parse.Promise();
    xmlReader.read(xlmString, function (err, res) {
        if(err) {
            promise.reject(err);
        } else {
            promise.resolve(res);
        }
    });
    return promise;
}

for (i = 0; i < urls.length; i++) {

    Parse.Cloud.httpRequest({
        url: unionUrls[i],
    }).then(function(httpResponse) {
            try {
//              console.log(httpResponse.text)
                return readResponse_async(httpResponse.text)
            } catch (e) {console.log(e)}

}

But now he did not wait for readResponse_async to finish, how can I wait for it?

thanks

EDIT

After reading the answer, I do a save in my database, and I have another array like this

var location = ['USA', 'England'];

And I do it like

function saveLoc_async(data, location) {
var i3, i4, i5, m,
            TestItem = Parse.Object.extend("TestItem"),//can be reused within the loops?
            promise = Parse.Promise.as();//resolved promise to start a long .then() chain
        for (i3 = 0; i3 < data.count(); i3++) {
             (function(testItem) {
                        testItem.set("item", data.at(i));
                        testItem.set("location", location);
                        //build the .then() chain
                        promise = promise.then(function() {
                            return testItem.save();
                        });
                    })(new TestItem());
//************************
//CALL  retry(); here?
//**************************

}

Because with your answer I have

function retry() {
if (urlsUnion.length > 0) {
    var nextUrl = urlsUnion.pop();
    //********** ADDED LINE
    var nextLoc = location.pop();

    Parse.Cloud.httpRequest({
        url: nextUrl,
    }).then(function(httpResponse) {
        xmlReader.read(httpResponse.text, function (err, res) {
            if(err) {
                // show an error
            } else {
                //********** ADDED LINE
                saveLoc_async(res, nextLoc);
                retry();
            }
        });
    });
}
}

SO, where should it retry();go, because now with saving sometimes it puts the second place with one of the first url elements? why does this happen?

Answer 1

URL .

, URL- . "then" , URL- .

(, , ):

var xmlReader = require('cloud/xmlreader.js');

function readResponse_async(xlmString) {
    xmlReader.read(xlmString, function (err, res) {
        if(err) {
            // show an error
        } else {
            readFirstUrl();
        }
    });
}

function readFirstUrl() {
    if (urlsUnion.length == 0) {
        return;
    }
    var url = urlsUnion.pop();
    Parse.Cloud.httpRequest({
        url: url,
    }).then(function(httpResponse) {
        readResponse_async(httpResponse.text);
    });
}

readFirstUrl();

Answer 2

- .

var actions = [drawXXX, fadeOutYYY, drawXYZ];


this.startAnimation = function () {
    actions.reduce(function (previousAction, nextAction) {
        return previousAction.then(nextAction)
    }, $.when());
}

Answer 3

, unionUrls, URL- urls, , :

function getUrl(url) {
      return Parse.Cloud.httpRequest(url)
                  .then( function(httpResponse) {
                     return readResponse_async(httpResponse.text);
                  });
}

urls.reduce( function(prev, url) {
   return prev ? prev.then( function() { getUrl(url); }) : getUrl(url);
 }, null);