protect.js

/**
 * Protect a callback based on a condition
 * @param  {Function} protector The condition to protect with
 * @param  {Function} protectee The callback to protect
 * @param  {Boolean}  not       Should the protector protect using
 *                              true or false results
 * @param  {mixed}    context   Optional context to call protector
 *                              and protectee with
 * @return {Function}           The protected callback
 */
function protect(protector, protectee, not, context) {

    if (typeof not === 'undefined') {
        not = false;
    }

    return function() {
        var result = protector.apply(context || this, arguments);
        
        if (typeof not === 'function') {
            not = not.apply(context || this, arguments);
        }

        if (not) {
            result = !result;
        }

        if (result) {
            return;
        }

        return protectee.apply(context || this, arguments);
    };
}