nodejs async same arguments to an array of functions?

Question

How do I apply the same arguments to an array of functions?

Works:

async.parallel([func(arg, arg2), func2(arg, arg2)],
function() {
  next();
});

The array has indeterminate / various functions functions inside though, so I'm not sure which functions I should be sending to the parallel method.

In various files I'm building the functions array:

funcArray.push(func2)

As a result I have an array like this:

[func, func2]

I would like to just do:

async.parallel(funcArray,
function() {
  next();
});

and have all the same arguments be applied to all the functions. How can I do this? Thanks.

Ended up writing my own:

  _.each(obj, function (func) {
    func(req, res, function () {
      i++
      if (i == objSize) {
        next()
      }
    })
  })

Jordan Running · Accepted Answer · 2011-08-29 23:11:51Z

2

Untested, but this ought to work:

var args      = [ arg, arg2 ]
  , funcCalls = []
;

for(var i = 0; i < funcArray.length; i++) {
  funcCalls.push(function() {
    funcArray[i].apply(this, args); }
  );
}

async.parallel(funcCalls, next);

Or, if you already know how many arguments you'll have, you don't need to use apply in the middle section:

for(var i = 0; i < funcArray.length; i++) {
  funcCalls.push(function() {
    funcArray[i](arg, arg2); }
  );
}

And finally you could really tighten it up with a map function as provided by e.g. Underscore.js:

async.parallel(_.map(funcArray,
  function(func) { return function() { func(arg, arg2); } }
), next);

...but then the next guy who comes across your code might kill you.

answered Aug 29, 2011 at 23:11

Jordan Running

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1 Comment

user1102171 Over a year ago

just use async.apply to add arguments to function. Refer to github.com/caolan/async#applyfunction-arguments

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