tslint Error - Shadowed name: 'err'

Question

tslint is currently throwing the following error

Shadowed name: 'err'

Here is the code

fs.readdir(fileUrl, (err, files) => {
        fs.readFile(path.join(fileUrl, files[0]), function (err, data) {
            if (!err) {
                res.send(data);
            }
        });
    });

Anybody have a clue on what the best way would be to solve this and what the error even means?

Answer 1

You are using the same variable "err" in both outer and inner callbacks, which is prevented by tslint.

If you want to use the same variable then "no-shadowed-variable": false, otherwise do as below.

fs.readdir(fileUrl, (readDirError, files) => {
    fs.readFile(path.join(fileUrl, files[0]), function (err, data) {
            if (!err) {
                res.send(data);
            }
        });
    });