Getting the return value from a generator in Node JS

Question

I can't seem to figure out how to get at the return value of a generator - anyone know what I am doing wrong?

function getGeneratorReturn() {
    var generator = runGenerator();
    var generatorReturn = null;

    var done = false;
    while(!done) {
        var currentNext = generator.next();
        console.log('Current next:', currentNext);
        generatorReturn = currentNext.value;
        done = currentNext.done;
    }

    return generatorReturn;
}

function* runGenerator() {
    var a = yield 1;
    var b = yield 2;
    var c = a + b;

    return c;
}

var generatorReturn = getGeneratorReturn();
console.log(generatorReturn); // Should output 3, is outputting NaN

Note: You'll need node 0.11.12 running with the --harmony option for this code to run.

Answer 1

When currentNext.done is true, curentNext.value has the return value.

You can write your loop as:

var next;
while (!(next = generator.next()).done) {
    var yieldedValue = next.value;
}
var returnValue = next.value;