a bug fix in assginDeep.js

[yanCode]

as described in this ticket, #4 , now I have got some time and provide my fix to it.

[bcherny]

Thanks for the contribution @yanCode! Does the code have the same problem for other class/function instances? If so, would it be better to use a simplified version of what lodash does?

[yanCode]

@bcherny , thanks for your reminder of testing other types, I did some tests, it turns out that the array type in a property still fails, like assignDeep({a: 1}, {b: [1,2,3]}).
which is a bit tricky, when it recursively calls the assignDeep on an array, if this array passes the test isObject, the assigned array turns to be {'0':1, '1':2, '2': 3}. on the other hand, if this array doesn't pass the isObject test, then the array is assigned using '=', well this is shallow copy.

the loadash implementation, still treats an array as an object. _.isObject([1,2]) === true

my conclusion is that it needs to add some specific logic to deep copy the array.

[bcherny]

You want _.isPlainObject, not _.isObject.

In any case, this seems to be the wrong path to go down. I've updated the blog post:

assignDeep - Like Object.assign, but merges objects deeply. For the sake of simplicity, you can assume that objects can contain only numbers and other objects (and not arrays, functions, etc.).