Is it possible to get data of two files like so using then function using bluebird promise?

Question

fs.readFileAsync('directory/file1.txt')
        .then(function(fileData1){
            return fs.readFileAsync('directory/file2.txt');
        })
        .then(function(fileData2){
            return console.log(fileData1+fileData2);
        })

http://stackoverflow.com/questions/30852343/convert-promise-to-bluebird — Jason Rice, Mar 30 '17 at 19:24

Jason Rice · Answer 1 · 2017-03-30T19:44:15.347

You can just wrap the first fs.readFileAsync('directory/file1.txt') call in Bluebird.resolve to convert to Bluebird promises, but you won't have the result of the first file in the handler of your second 'then' function.

In your case you can do them both in parallel using Bluebird.all.

Bluebird.all([
  fs.readFileAsync('directory/file1.txt')
, fs.readFileAsync('directory/file2.txt')
])
  .spread(function(file1, file2) {
    console.log(file1 + file2);
  })

If you use Bluebird.all remember that it takes an Array.

Is it possible to get data of two files like so using then function using bluebird promise?

1 Answers1