next api for async

next-usage.js

// **Compares to waterfall**
// waterfall usage
async.waterfall([
    function(callback){
        callback(null, 'one', 'two');
    },
    function(arg1, arg2, callback){
        callback(null, 'three');
    },
    function(arg1, callback){
        // arg1 now equals 'three'
        callback(null, 'done');
    }
], function (err, result) {
   // result now equals 'done'    
});

// next usage
async.next(function (arg1, arg2, callback) {
    // arg1: 'one', arg2: 'two'
    callback('three');
}).next(function (arg1, callback) {
    // arg1: 'three'
    callback('done');
}).next(function (arg1) {
    // arg1: 'done'
})('one', 'two'); //start



// **Resuable**
var process = async.next(function (data, next) {
    // step1, do something
    next(data); 
}).next(function (data, next) {
    // step2, do something...
    next(data);
});

var data1   = new Data();
process(data1);

var data2   = new Data();
process(data2);


// **Also appendable**
process.next(function (data, next) {
    // step3, do something
    next(data)
});

var data3   = new Data();
process(data3);



// **'this' context**
var obj = {
    value   : 1,
    run     : async.next(function (v, next) {
                console.log(this.value); // 1

                this.value = v;
                next();
            }).next(function (data, next) {
                console.log(this.value); // 2
            })
};
obj.run(2);

// source code here
// https://github.com/rhyzx/Lab/blob/master/next-async.js