How best to implement out params in JavaScript?

Question

I\'m using Javascript with jQuery. I\'d like to implement out params. In C#, it would look something like this:

/*
 * odp      the object to test
 * error            


        

Answer 1

I am using a callback method (similar to Felix Kling's approach) to simulate the behavior of out parameters. My answer differs from Kling's in that the callback function acts as a reference-capturing closure rather than a handler.

This approach suffers from JavaScript's verbose anonymous function syntax, but closely reproduces out parameter semantics from other languages.

function isLegal(odp, out_error) {
    //...
    out_error("ODP failed test foo"); // Assign to out parameter.
    return false;
}

var error;
var success = isLegal(null, function (e) { error = e; });

// Invariant: error === "ODP failed test foo".