Extremely Basic Asynchronous Loop

basicAsyncLoop.js

var iterationCount = 3;
function doIterations(cb) {
    if (iterationCount !== 0) {
        // print the number of iterations, then wait 5 seconds
        setTimeout(function(){ console.log(iterationCount); iterationCount --; doIterations(cb); }, 500);
    }
    else {
        // now that we're done, fire the callback (if one exists)
        cb && cb();
    }
}

doIterations(function() { console.log('donezo!'); });

// prints:
// 3
// 2
// 1
// donezo!