javascript - nodejs 异步 : How to use a loop containing an asynchronous call within an "async.series" function block

Question

在使用基于 async.series 的设计时，我必须在功能 block 中使用循环，如下所示:

var someFile = filePath;
async.series([
    function(cb) {
         _.forEach (
               someDataList,
               function (item) {
                   //call that executes out of sync
                   writeToFile(someFile,item)
                   //how to provide callback here
                   cb(); //<- is this correct - won't this take control out of this block in the very first loop iteration?
               }
         );
    }
],
//callback function
function (err) {...}
);

Answer 1

您可以改用 forEachSeries。

var someFile = filePath;
async.forEachSeries(someDataList, function(item, cb) {
   writeToFile(someFile, item)
   cb();
},
//callback function
function () {...}
);

评论后更新:

不幸的是，无法在 forEachSeries 中获取迭代对象的索引。如果你想要 iteratee 的索引，你可以使用 eachOfSeries

var someFile = filePath;
async.eachOfSeries(someDataList, function(value, key, callback) {
    //Do something with key
    writeToFile(someFile, item)
    callback();
}, //callback function
function () {...}
);