[Solved] Identify the error in this NgRx reducer code:function todoReducer(state = [], action) { if (action.type === 'add') { state.push(action.payload); return state; } return state; } | Angular

Angular - State Management

Identify the error in this NgRx reducer code:

function todoReducer(state = [], action) {
  if (action.type === 'add') {
    state.push(action.payload);
    return state;
  }
  return state;
}

AMutating state directly instead of returning a new state

BMissing default case in reducer

CIncorrect action type string

DReducer should not return state

Step-by-Step Solution

Solution:

Step 1: Check state mutation
The reducer uses state.push(), which changes the original array directly.
Step 2: Understand NgRx immutability rule
Reducers must return new state objects without mutating the old state.
Final Answer:
Mutating state directly instead of returning a new state -> Option A
Quick Check:
Reducers must be pure and immutable [OK]

Quick Trick: Never mutate state; always return new object/array [OK]

Common Mistakes:

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