Reduce function for an object

reduce-obj.js

function reduceObject(obj, fn, init) {
    return Object.keys(obj).reduce(function (accum, key) {
        return fn(accum, obj[key], key, obj);
    }, init);
}

// usage

var obj = {
  a: [1,2,3],
  b: [4,5,6],
  c: [7,7,7]
};

reduceObj(obj, function(accum, val, key, object) {
  return accum.concat(val);
}, []);

// [1,2,3,4,5,6,7,7,7]