Question

I have been playing with NodeJS lately and i found myself stuck with a regular pattern issue :

I have a main operation running on, depending on some config parameters, i need to perform an extra step, but this step is async :

    if(request.config.save) {

        fs.writeFile(request.config.save, decryptedData, function(err) {
            // Continue the operation with a callback...
            // Perform some other ops.
            if(typeof callback == 'function') callback(decryptedData);
        }.bind(this));

    } else {

        // Continue the same operation without a callback
        // Perform some other ops.
        if(typeof callback == 'function') callback(decryptedData);

As you can see this code is not DRY as the main ending (callback) is called twice.

Only way I see is to use functions (but once again the function call is not DRY… And code could be really bloated this way…

So is there a pretty ninja trick to solve this?

Answer 1

Well, a single line of code isn’t all that repetitive, but if you’re doing more than that it can get very non-dry. What about just wrapping your final logic into a function, and calling that inside your conditionals?

var endTick = function(){
    if(typeof callback == 'function') callback(decryptedData);
}

if(request.config.save) {

    fs.writeFile(request.config.save, decryptedData, function(err) {
        // Continue the operation with a callback...
        // Perform some other ops.
        endTick();
    }.bind(this));

} else {

    // Continue the same operation without a callback
    // Perform some other ops.
    endTick();
}