nodeJS return value from callback

Question

I am building an application in which on a particular call, i must block and wait for the results from an authentication query before coninuing.

function aut         


        

Answer 1

Your outer function needs to provide a callback itself which can be executed once the mysql call is done. Something along the lines of this:

function authenticate(user, pass, callback) {
    mysql_client.query("...", function (err, results, fields) {
        if (err) {
            callback("Error communicating ...");
        } else if (results.length ...) {
            callback("Error comparing authentication...");
        }
        callback()
    });
});

Example usage:

authenticate('jim', '123456', function (err) {
    if (err) {
        alert(err);
    } else {
        alert('Welcome');
    }
});