Trampoline implementation example

trampoline.js

// http://jsfiddle.net/4yTPD/

debugger;
function sum (n) {    
    function nextStep (m, result) {
        return function () {            
            if (m === 1) return result;
            return nextStep(m-1, result + m);
        }
    }
    return nextStep(n, 1)();
}

function trampoline (fn) {
    while (_.isFunction(fn)) {
         fn = fn.call(null);   
    }
    return fn;
}

alert(trampoline(function () { return sum (30000) }));