在Node.js中，async.map不会调用回调函数。

Question

我正在尝试使用async.map，但无法调用回调函数，原因未知。在下面的示例中，函数d应该显示数组r，但它却没有显示出来。实际上，似乎从未调用d。我一定做错了什么，但无法弄清楚是什么。

async = require('async');
a= [ 1,2,3,4,5];
r=new Array();

function f(callback){
    return function(e){
        e++;
        callback(e);} 
}

function c(data){ r.push(data); }

function d(r){ console.log(r);}

async.map(a,f(c),d);

感谢您提前的帮助。

- user3097050

---

var fc = f(c); // fc没有回调参数，这就是问题 - damphat

Answer 1

var async = require('async');

//This is your async worker function
//It takes the item first and the callback second
function addOne(number, callback) {
  //There's no true asynchronous code here, so use process.nextTick
  //to prove we've really got it right
  process.nextTick(function () {
    //the callback's first argument is an error, which must be null
    //for success, then the value you want to yield as a result
    callback(null, ++number);
  });
}

//The done function must take an error first
// and the results array second
function done(error, result) {
  console.log("map completed. Error: ", error, " result: ", result);
}

async.map([1,2,3,4,5], addOne, done);

- Peter Lyons