javascript - Control flow: Run two asynchronous array maps -

i have 2 functions asynchronous – accept function parameter called when done (callback).

function a(item, cb) {   someasyncoperation(function () {     cb(item)   }) }  function b(item, cb) {   someasyncoperation(function () {     cb(item)   }) } 

i have array. need run these functions, using array.prototype.map, on array 2 times. when both maps done, have callback invoked 2 parameters: error , mapped array.

what sort of control flow need achieve this? in async library i'm guessing.

in pseudo-ish code:

var example = [1, 2, 3]  async.series([   function () { example.map(a) },   function () { example.map(b) } ], function (error, mappedexample) {  }) 

you can use async library sort of thing, in case, can handle chaining functions together:

var items = ["a", "b", "c", "d" ],     foo = function (array, cb) {         "use strict";         array = array.map(function (element) {             return "foo-" + element;         });          cb(array);     },     baz = function (array) {         "use strict";         array = array.map(function (element) {             return "baz-" + element;         });          console.log(array);     };  foo(items, baz); 

results in:

[ 'baz-foo-a', 'baz-foo-b', 'baz-foo-c', 'baz-foo-d' ] 

if functions particularly complex or sort of thing often, async can of help; however, there no reason why can't on own. (you need add error handling of course)