mapValuesDeep mutates the original object if leavesOnly: false

[lewisblackwood]

Hi,

Great library 👍

I found using mapValuesDeep that if the options are left at the default leavesOnly: false, then it mutates the original object. If leavesOnly: true then the original object is not mutated.

You can see an example repl.it here.

// leavesOnly: true
{ sourceData: { hello: 'world' }, mappedData: { hello: 'WORLD' } }
// leavesOnly: false
{ sourceData: { hello: 'WORLD' }, mappedData: { hello: 'WORLD' } }

Is this the expected behaviour?

[YuriGor]

Hi, thank you for report, looks like a bug, will check in next few days.

[YuriGor]

If leavesOnly is false, it will call your callback for middle object values also, not only for primitive/childless 'leaves'.
So you return original object v here:
const iteratee = (v, k) => k === "hello" ? v.toUpperCase() : v
And it's placed to the result as provided by you.
So in result object you have same references as in source.

After that deepdash goes deeper and asks about leaf string value, but this leaf already belongs both to source and result objects, because they were mixed on previous iteration.
So it's not mapValuesDeep mutates the original object, it's you :)
If you want to go over non-leaf nodes (from your example it's not clear why do you need it) - don't return original nodes by reference, always replace them by something or clone.