Question

我有这个简单的代码似乎与async.waterfall的使用方式一致，但我提到了这个TypeError：

var myCallback = function (data){
  console.log("task done for " + data);
}

var test = function (param,callback) {
  console.log("in test, doing some work, param is: " + param);
  callback(param);
};

async.waterfall([
  test("call 1",myCallback),
  test("call 2",myCallback),
  test("call 3",myCallback)
],  function (err, result) {
    // result now equals 'done'
});

执行结果是：

in test, doing some work, param is: call 1
task done for call 1
in test, doing some work, param is: call 2
task done for call 2
in test, doing some work, param is: call 3
task done for call 3
/Users/.../Documents/.../node_modules/async/dist/async.js:5021
            task.apply(null, args);
                ^

TypeError: Cannot read property 'apply' of undefined
    at nextTask (/.../node_modules/async/dist/async.js:5021:17)
    at Object.waterfall (/.../node_modules/async/dist/async.js:5024:9)
    at Object.<anonymous> (/.../app.js:77:7)
    at Module._compile (module.js:409:26)
    at Object.Module._extensions..js (module.js:416:10)
    at Module.load (module.js:343:32)
    at Function.Module._load (module.js:300:12)
    at Function.Module.runMain (module.js:441:10)
    at startup (node.js:139:18)
    at node.js:968:3

我一直在四处寻找，但找不到问题 - 欢迎一些帮助。非常感谢！ ç

Answer 1

尝试以下代码：

async.waterfall([
    function(callback) {
        task1().then(function(){
            callback(data)
        })
    },
    function(data1, callback) {
        task2().then(function(data2){
            callback(data1, data2)
        })
    }
], function(err, data1, data2) {
    console.log('data');
});

您的代码无效，因为无法调用最终回调并尝试调用另一个不存在的任务。

async - TypeError：无法读取属性＆＃39; apply＆＃39;未定义的

1 个答案: