Question

I have the following function:

//translate strings
function translate(lng, str)
{
    var translation = '';
    csv().from(__dirname + '/../application/_common/lng/' + lng + '.csv', {delimiter: ';'})
    .transform( function(row, index) {
        if(row[0] == str) {
            return row[1];
        }
    })
    .on('data', function(data) {
        translation = data;
    })
    .on('end', function() { return translation; });
}

and I want to get the value found in the csv into a variable like this:

var translation = translate(‘en’, ‘translate_me’);

The problem is that the function does not return anything!

Answer 1

Well, you don’t return anything, you only return things from inner functions, but the outer function doesn’t. If CSV is synchonous, do this:

function translate(lng, str)
{
    var translation = '';
    csv().from(__dirname + '/../application/_common/lng/' + lng + '.csv', {delimiter: ';'})
    .transform( function(row, index) {
        if(row[0] == str) {
            return row[1];
        }
    })
    .on('data', function(data) {
        translation = data;
    })
    .on('end', function() { return translation; });  // This just returns something from the inner function, which has no effect.
    return translation; // actually return the translation
}

If CSV is _asynchronous, it gets a little bit harder. Do this:

function translate(lng, str, callback) // Note the extra parameter
{
    var translation = '';
    csv().from(__dirname + '/../application/_common/lng/' + lng + '.csv', {delimiter: ';'})
    .transform( function(row, index) {
        if(row[0] == str) {
            return row[1];
        }
    })
    .on('data', function(data) {
        translation = data;
    })
    .on('end', function() { callback(translation); }); // call the callback
}

Now you would call it like this:

var translation;
translate('en', 'translate_me', function(val){ translation = val; });