Why isn't this forEach look pushing the data to this outer variable?

Question

I want to read the content of input (a folder) and push the result into input2 (an array):

 const input = process.argv[2]
 var input2 = []

 if (process.argv.length < 3) {
   console.log('Usage: node ' + process.argv[1] + ' FILENAME')
   process.exit(1)
 }

 fs.readdir(__dirname + `/${input}/`, (err, files) => {
    if (err) {
      console.log(err)
      return
    }

    files.forEach((file) => {
      console.log(file)
      fs.readFile(__dirname + `/${input}/` + file, 'utf8', (err, data) => {
        if (err) {
          console.log(err)
        }
        console.log(data)
        input2.push(data)
      })
    })
  })

 console.log(input2)

console.log(data) does log the values:

## Chapter 1

Paragrhap 1

## Chapter 2

Paragrhap 2

But console.log(input2) logs []

What am I doing wrong?

You're forgetting that the Filesystem APIs are **asynchronous**. — Pointy, May 18 '15 at 11:55

score -1 · Answer 1 · answered May 18 '15 at 11:59

you must write the console.log in end of foreach

 const input = process.argv[2]
 var input2 = []

if (process.argv.length < 3) {
console.log('Usage: node ' + process.argv[1] + ' FILENAME')
process.exit(1)
}

fs.readdir(__dirname + `/${input}/`, (err, files) => {
    if (err) {
      console.log(err)
      return
    }

files.forEach((file) => {
  console.log(file)
  fs.readFile(__dirname + `/${input}/` + file, 'utf8', (err, data) => {
    if (err) {
      console.log(err)
    }
    console.log(data)
    input2.push(data)
  })
})
 console.log(input2)

})

This still won't work, because `.readFile()` is *also* asynchronous. — Pointy, May 18 '15 at 12:08

Why isn't this forEach look pushing the data to this outer variable?

1 Answers1