Question

解决以下控制流程的最佳方法是什么：

我只想在getSomeOtherData等于某个值时调用someData /通过一些条件测试
在这两种情况下，我总是想致电getMoreData

http.createServer(function (req, res) {
    getSomeData(client, function(someData) {
        // Only call getSomeOtherData if someData passes some conditional test
        getSomeOtherData(client, function(someOtherData) {
           // Always call getMoreData
           getMoreData(client, function(moreData) {
             res.end();
           });
       });
   });
});

Answer 1

没有很好的解决方案;我发现最好的是创建一个本地函数来处理剩下的常见工作：

http.createServer(function (req, res) {
  getSomeData(client, function(someData) {
    function getMoreAndEnd() {
       getMoreData(client, function(moreData) {
         res.end();
       });
    }

    if (someData) {  
      getSomeOtherData(client, function(someOtherData) {
        getMoreAndEnd();
      });
    } else {
      getMoreAndEnd();
    }
  });
});

Answer 2

这是你想要的吗？

http.createServer(function (req, res) {
    getSomeData(client, function(someData) {
        function myFunction (callback) {
            // Only call getSomeOtherData if someData passes some conditional test
            if (someData) {
                getSomeOtherData(client, function(someOtherData) {
                   // Do something.
                });
            }

            callback();
        }

        myFunction(function () {
            // Always call getMoreData
            getMoreData(client, function(moreData) {
                res.end();
            });
        });
    });
});

有条件地执行回调

2 个答案: