assocIn

assocIn

assocIn is a function that takes an array indicating a path within an object, a value to set at that path, and the object itself. It returns a new object with the value at that path set to the provided value.

For example, with the object const obj = { name: { first: "Winston", last: "McDermott" }, age: 28 }, the path to the last name would be ['name', 'last']. To change the last name to 'Smith':

assocIn(['name', 'last'], 'Smith', obj)

which should return { name: { first: "Winston", last: "Smith" }, age: 28 }

If the path does not exist in the target object, it should be created:

const obj = { age: 28 }
assocIn(['name', 'last'], 'Smith', obj) // returns `{ name: { last: 'Smith' }, age: 28 }` // the `name` object was created

It should handle undefined (and null) gracefully:

assocIn(['name', 'first'], 'Winston', null) // returns `{ name: { first: 'Winston' } }` // the entire object was created

An empty path should return the entire original object:

assocIn([], 'Smith', { name: { first: 'Winston' } }) // returns `{ name: { first: 'Winston' } }` // the object was returned unaltered

Note: your function should not mutate the input object.