generator example

generator-test.js

var commonJs = function(src,callback){
   setTimeout(function(){
       callback(null,{
         src:src,
         style:"commonJs"
       });
   },100);
}
var commonJsError = function(src,err,callback){
   setTimeout(function(){
       callback(new Error(err));
   },100);
}
var promise = function(src){
    return new Promise(function(resolve,reject){
        setTimeout(function(){
            resolve({
              src:src,
              style:"promise"
            });
        },100)
    });
}
var readMultipleFiles = async(function* (){
    var json1 = yield commonJs.bind(null,'test1.json');
    var json2 = yield commonJs.bind(null,'test2.json');
    var json3 = yield promise('test3.json');
    var json4 = yield commonJsError.bind(null,'test4.json','error');
    var json5 = yield commonJs.bind(null,'test5.json');
    console.log(json1);
    console.log(json2);
    console.log(json3);
});

//test function
readMultipleFiles();

generator.js

function async(makeGenerator){
    return function (){
        var generator = makeGenerator.apply(this, arguments);
        function handle(result){ // { done: [Boolean], value: [Object] }
            if (result.done) {
                return result.value;
            }
            if(result.value.then){
              return result.value.then(function (res){
                  return handle(generator.next(res));
              }, function (err){
                  return handle(generator.throw(err));
              });
            }else{
              return result.value(function(err,res){
                if(err){
                  handle(generator.throw(err));
                }else{
                  handle(generator.next(res));
                }
              });
            }
            
        }
        return handle(generator.next());
    }
}