Still confused about callback function of filesystem in javascript

Asked May 26 '17 at 14:32

Active May 26 '17 at 14:54

Viewed 27 times

I have read some question about callback. But still can't understand. I write this code to store file into an array.

var admList; // The array I want to store in

let readList =(fPath, callback)=>fs.readFile(fPath, 'utf8', (err, fd) => {
      if (err) console.error(fPath+'does not exist');
      callback(fd); // set a callback 
});


readList('admList', function (fd) {
    admList = fd.toString().trim().split('\n'); //using it
});
console.log(admList); // undefined

Am I already using a callback function? Why in the console it's still undefined?

edited May 26 '17 at 14:54

asked May 26 '17 at 14:32

Dong Yibo

1

What does it mean " Why can't I make it work"? Are you getting any errors or what? – Yury Tarabanko May 26 '17 at 14:37
1

Yes, you're using `fd` correctly inside a callback function. But you're likely not using `admList` correctly outside the callback function, in the code that you haven't shown. – Bergi May 26 '17 at 14:37
When I using the 'admList', it's still 'undefined'. – Dong Yibo May 26 '17 at 14:43

Still confused about callback function of filesystem in javascript

0 Answers0