Loading string array from text file and searching for specific value

Question

I'm coding a simple chat browser application with Node.js. To keep multiple users from using the same name, I store all user's names in an array

userList.push(socketName);

and every time someone connects, I look for his name in this array

function inList(name, list) {
  if(list.indexOf(name) === -1)
    return false;
  return true;
}

This work perfectly. My problem is I also want to check a white list in an external text file, which have a single name per line. My code for that is

let temp = fs.readFileSync('./list.txt', 'UTF-8');
var whiteList = temp.split('\n');
if(inList(socketName, whiteList)) {
   //let user join
}

It is the same logic, I'm just loading the list from a file. In this case, function inList() will return true only if the name tested is in the last line of the file. Any of the other names in the list will cause it to return false, and I have no idea why.

I thought the string.split('\n') could leave the '\n' on the returned array, so I tried printing all whiteList[] elements on console and on another file and found nothing.

I'm actually not that experienced with javascript and would appreciate any help

Thanks!

edit: Solved it as suggested by @Barmar using

var whiteList = temp.split('\n').map(s => s.trim());

Thank you everyone for your help!

@justcodin In my tests it was: Mefa ADM_Sam Test I can only log with the last name, in this case being "Test" — Femen, Feb 04 '21 at 00:26
@justcodin I think the comment section don't accept \n, but my file is Mefa\nADM_Sam\nTest, it looked like the array was alright when I printed it — Femen, Feb 04 '21 at 00:30
FYI, JavaScript has a function that does what `inList()` does: `if (whiteList.includes(socketName))` — Barmar, Feb 04 '21 at 00:30
Try using `var whiteList = temp.split('\n').map(s => s.trim());` to remove any surrounding whitespace. — Barmar, Feb 04 '21 at 00:33
I don't know what kind of noise was getting into the array, but .map(s => s.trim()) solved it! — Femen, Feb 04 '21 at 00:45

score 0 · Answer 1 · answered Feb 04 '21 at 00:32

0

Try this :

const temp = fs.readFileSync('./list.txt', 'utf8');
const whiteList = temp.trim().split('\n');
const isLastItem = whiteList[whiteList.length - 1] === name;

answered Feb 04 '21 at 00:32

justcodin

857
7
17

Trimming the whole file wasn't exactly the solution, but thanks for the insight! – Femen Feb 04 '21 at 00:47

Loading string array from text file and searching for specific value

1 Answers1