Hey I just met you, and this is crazy, but here's my callback, so definitely call it once, and once only.
This tiny module is meant to help debug pesky asynchronous code by making sure your callbacks are called just once. It also checks if the given callback is undefined or if it's called in the same event loop.
This is meant to be used during testing, not production code. But could be used to help debug.
var callme = require('callme');
function asyncMethod(a, b, callback) {
callback = callme(callback);
someIO(a, b, function(err, result) {
if (err) callback(err);
result = permuteTheResult(result);
// this will throw if there is an error since it will be
// the second time the callback is called.
// a `return` was forgotten on the error check above.
callback(err, result);
});
}
The callme
function returned is also an instance of EventEmitter
. If you prefer to listen to the error
event instead, you can do so.
function asyncMethod(a, b, callback) {
callback = callme(callback);
callback.on('error', function(err) {
// do something with `err`
});
someIO(a, b, function() {
// etc
});
}
It also supports a timeout
option, make sure your callbacks are definitely called.
function asyncMethod(a, b, callback) {
callback = callme(callback, 2000); // set timeout to 2 seconds
callback.on('error', function(err) {
// this will fire in 2 seconds since `callback` is never called
});
}
npm install callme
Tests are written with mocha
npm test
MIT