Node.js Tutorial => async.js

30% OFF - 9th Anniversary discount on Entity Framework Extensions until December 15 with code: ZZZANNIVERSARY9

Syntax

Each callback must be written with this syntax:
function callback(err, result [, arg1[, ...]])
This way, you are forced to return the error first, and can't ignore handling them later on. null is the convention in absence of errors
callback(null, myResult);
Your callbacks can contain more arguments than err and result, but it's useful only for a specific set of functions (waterfall, seq, ...)
callback(null, myResult, myCustomArgument);
And, of course, send errors. You must do it, and handle errors (or at least log them).
callback(err);

PDF - Download Node.js for free

Previous Next