How to use Try/Catch to read files

Question

I have a method called readFileCredentials which aims to open a file and return the data that was inside that file, follows the code of that method:

readFileCredentials = function(file, cb){
    var _path = 'data-source/credentials/' + file;
    fs.readFile(_path, 'utf8', function(err, data){
        cb(err, data); 
    });
};

And to call this method, I built this code:

try{    
    readFileCredentials('arquivo.txt', function(err, data){
         console.log('Abriu');
    });
}catch(err){
    console.log('Não abriu');
}

The read is working, however, when I send a wrong file name, so there is an error, the catch is not triggered, what is wrong?

Answer 1

The method fs.readFile already does it for you, to avoid generating errors that stop the code. Your idea is good, but it is not necessary. You can take a look at the source code of fs on Github.

What would be caught in the catch is passed to the variable err, so your logic should depend on that variable and not on a try/catch:

You can do it like this:

fs.readFile(_path, 'utf8', function(err, data){
    console.log(err ? 'Nao abriu' : 'Abriu');
    cb(err, data); 
});