CODEWITHSUNDEEP
javascriptnode.jspromisecommand-line-interface
Scott Anderson
Scott Anderson

Reputation: 693

Node strange user input async behaviour

I am just getting used to Node programming, but I have come across this execution issue which I am slightly confused about.

I am trying to test if a write path already exists and if it does then ask the user for input. 

function testPath(fileName) {
  fs.exists(path.resolve('.', fileName), function(exists) {
  //the filepath already exists, ask for user confirmation
  if(exists) {
    process.stdin.on('keypress', function (str, key) {
    //print result of keypress to console
    console.log("str: ", str, " key: ", key);

    if ((str.toLowerCase() == "n") || (~["y", "n"].indexOf(str.toLowerCase()))) {
      return false;
    }
    else {
      return true;
    }
  });
  }
  else {
  //the filepath does not already exist - return true
  return true;
}
console.log("Filename in the target directory already exists, would you like to overwrite? (y/n)");
});
}

This function as a whole will be be resolved (or not) by a promise called on it.

The message to user and wait for keypress seem to action in the correct way but it sticks in a loop and never returns even on a valid keypress, does anyone know why this would be?

Upvotes: 1

Views: 41

Answers (1)

Danilo Souza Morães
Danilo Souza Morães

Reputation: 1593

If you want to use it as a promise, you need to return a promise:

function testPath(fileName) {
    return new Promise((resolve, reject) => {
        fs.exists(path.resolve('.', fileName), function(exists) {
        //the filepath already exists, ask for user confirmation
        if(exists) {
            process.stdin.on('keypress', function (str, key) {
            //print result of keypress to console
            console.log("str: ", str, " key: ", key);

            if ((str.toLowerCase() == "n") || (~["y", "n"].indexOf(str.toLowerCase()))) {
            return reject();
            }
            else {
            return resolve();
            }
        });
        }
        else {
        //the filepath does not already exist - return true
        return resolve();
        }
        console.log("Filename in the target directory already exists, would you like to overwrite? (y/n)");
        });
        }
    })

Upvotes: 2

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