Learning Redux

Common mistake 2 - Only making a shallow copy

A very common mistake is only copying one level of a nested object.

Consider the following example:

const brokenReducer = (state, action) => {  let newState = { ...state }  newState.nestedState.nestedField = action.data  return newState}

In this case, the preceding highlighted line modifies the original state.nestedState object because we only made a shallow copy of the root object.