function Next(){
    this.funcs = [];
}
Next.prototype.next = function(callback){
    this.funcs.push(callback);
    return this;
}
Next.prototype.start = function(){
    var func = this.funcs.shift();
    func && func.apply(this,arguments);
}
exports = module.exports = Next;

下面是测试代码

var Next = require('./next.js');
var next = new Next();
var fs = require('fs');

next.next(function(a){
    fs.stat(__filename, function (e,stat) {
        if(e) throw e;
        console.log(a);
        next.start(stat);
    })
}).next(function(stat){
    fs.access(__filename, function (e) {
        console.log('this file size=' + stat.size);
        next.start( e ? false : true);
    })
}).next(function(exists){
    console.log('exists = '+exists);
}).start('start');

console.log('helloworld'+ next);