get all keys from an object, nested or otherwise.

getAllKeys

Array.prototype.flatten = function () {
    return this.reduce(function (all, current) {
        if (current.constructor === Array) return all.concat(current.flatten());
        else return all.concat(current);
    },[]);
}
function getAllKeys(obj) {
    return Object.keys(obj).reduce(function (allKeys, key) {
        var val = obj[key];
        if (val.constructor === Array) {
            allKeys.push(key);
            allKeys = allKeys.concat(val.map(getAllKeys).flatten());
        } else {
            allKeys.push(key);
            var nestedKeys = Object.keys(val);
            if (nestedKeys.length)
                allKeys = allKeys.concat(getAllKeys(val));
        }
        return allKeys;
    }, []);
}

// test
getAllKeys({'a':1, 'b':{'c':2}, 'd': [{'e': 3}, { 'f': { 'g': 4 } }], 'h': [1,2,3]})
// should return: ["a", "b", "c", "d", "e", "f", "g", "h"]