Join dictionaries of arrays in JavaScript -

first of all, come obj-c , python, feel free edit faults in javascript teminology.

i looking efficient way of joining multiple dictionaries in javascript, each key can exist in more 1 dictionary , values arrays.

for example, have:

{foo: [1,2], bar: [3,4]} {foo: [5,6], baz: [7,8]} 

and want join values of same key, meaning should return:

{foo: [1,2,5,6], bar: [3,4], baz: [7,8]} 

i started doing following pseudo code, feel there should more efficient way of doing it.

// pseudo code return_value = {} (subset in full_array)     (kv in subset)         data = return_value[kv] || []         data.push(subset[kv])         return_value[kv] = data 

with lo-dash:

var data = [     {foo: [1,2], bar: [3,4]},     {foo: [5,6]}, ];  _.reduce(data, function (result, obj) {     _.each(obj, function (array, key) {         result[key] = (result[key] || []).concat(array)     })     return result }, {}) 

see fiddle.