节点-等待周期内的请求响应

Question

Really, I've tried all ways, but I fail to find the solution.

As no English, and I'm using the google translator, I will explain the same thing several times in a row.

1º Try the For loop will wait until everything is finished within

2º I try to know that city is doing OK on an external web request. And like many cities, I need to break the cycle once I check the first city ok.

3º I need to go a json and execute an action while running and wait till it finishes to follow. Then get out of the cycle at any time.

---

I've been testing with several codes, but present here for better understanding.

---------------------------------------------------------------------

var city = 
[
    {'city':'madrid'},
    {'city':'barcelona'},
    {'city':'valencia'},
    {'city':'malaga'}
];

var vBreak = 0;

for (i in city){

    request('example.there-city.com/' + city[i].city ,function (error, response, read) {
        if (read == 'OK') { vBreak = 1}
    });

if (vBreak == 1){ break;}
}

---

var city = 
[
    {'city':'madrid'},
    {'city':'barcelona'},
    {'city':'valencia'},
    {'city':'malaga'}
];

var vBreak = 0;

for (i in city){

    (function(i) {
        request('example.there-city.com/' + city[i].ciudad ,function (error, response, read) {
            if (read == 'OK') { vBreak = 1}
        });
    })(i);

if (vBreak == 1){ break;}
}

Thank you

Answer 1

Use async.eachSeries (as jgillich said) to perform each request in order like this:

async.eachSeries(city, function (item, cb) {
  if (vbreak !== 1) {
    request('example.there-city.com/' + item.city ,function (error, response, read) {
        if (read == 'OK') { vBreak = 1}
        cb();
    });
  } else {
    cb() // Skip
  }
}, function () { // we're finished
})

You'll need to add error handling probably.

Answer 2

Try to use a recursive function. Just increment the counter, after the response came ...