更新:

现在，我建议看看:

• 承诺

• Promises

Promise对象用于延迟和异步计算. Promise表示尚未完成的操作，但是 预计在未来.

The Promise object is used for deferred and asynchronous computations. A Promise represents an operation that hasn't completed yet, but is expected in the future.

一个流行的Promise库是 bluebird . A建议您查看为什么要承诺.

A popular promises library is bluebird. A would advise to have a look at why promises.

您应该使用promise来解决这个问题:

You should use promises to turn this:

fs.readFile("file.json", function (err, val) {
    if (err) {
        console.error("unable to read file");
    }
    else {
        try {
            val = JSON.parse(val);
            console.log(val.success);
        }
        catch (e) {
            console.error("invalid json in file");
        }
    }
});

对此:

fs.readFileAsync("file.json").then(JSON.parse).then(function (val) {
    console.log(val.success);
})
.catch(SyntaxError, function (e) {
    console.error("invalid json in file");
})
.catch(function (e) {
    console.error("unable to read file");
});

var co = require('co');

co(function *(){
  // yield any promise
  var result = yield Promise.resolve(true);
}).catch(onerror);

co(function *(){
  // resolve multiple promises in parallel
  var a = Promise.resolve(1);
  var b = Promise.resolve(2);
  var c = Promise.resolve(3);
  var res = yield [a, b, c];
  console.log(res);
  // => [1, 2, 3]
}).catch(onerror);

// errors can be try/catched
co(function *(){
  try {
    yield Promise.reject(new Error('boom'));
  } catch (err) {
    console.error(err.message); // "boom"
 }
}).catch(onerror);

function onerror(err) {
  // log any uncaught errors
  // co will not throw any errors you do not handle!!!
  // HANDLE ALL YOUR ERRORS!!!
  console.error(err.stack);
}

如果我正确理解，我认为您应该看看非常好的 async 库.您尤其应该看一下系列.只是github页面片段中的一个副本:

If I understand correctly I think you should have a look at the very good async library. You should especially have a look at the series. Just a copy from the snippets from github page:

async.series([
    function(callback){
        // do some stuff ...
        callback(null, 'one');
    },
    function(callback){
        // do some more stuff ...
        callback(null, 'two');
    },
],
// optional callback
function(err, results){
    // results is now equal to ['one', 'two']
});


// an example using an object instead of an array
async.series({
    one: function(callback){
        setTimeout(function(){
            callback(null, 1);
        }, 200);
    },
    two: function(callback){
        setTimeout(function(){
            callback(null, 2);
        }, 100);
    },
},
function(err, results) {
    // results is now equals to: {one: 1, two: 2}
});

此外，该库还可以在浏览器中运行.

As a plus this library can also run in the browser.