Update javascript parent variable from a callback

Question

In node.js I need to collect some data across multiple callbacks and store them in one object. I tried the following code, but the collected data is not saved in the initialized variable. Can you pls help what I'm doing wrong?

My code:

for (var x in data) {
    var status = {items: []};

    for (var y in x) {
        do_something(y, function (err, res) {
            again_do_something(res, function(err, result) {
                status.items.push({key: result});
            });
         });
     }

     console.log(status); //Here I got only {items: []}
}

thefourtheye · Accepted Answer · 2013-10-12 12:17:41Z

3

console.log(status);

will be getting executed before the callback function getting executed. Thats why you are seeing empty.

One easy way to solve this common problem is to use async library's concat method.

edited Oct 12, 2013 at 12:17

answered Oct 12, 2013 at 12:07

thefourtheye

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2 Comments

filo891 Over a year ago

Thanks! I've missed that. But then how can I track down when has the last callback been executed so I can pass the collected data forward?

thefourtheye Over a year ago

@filo891 Updated my answer with async library solution. Please check.

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