CODEWITHSUNDEEP
typescript
user1354934
user1354934

Reputation: 8841

TypeScript error number is not assignable

I am writing a reducer and I want RESET to do state.count = 0. However, this gives me an error that number is not assignable to type CounterState.

Here is my code:

export interface CounterState {
  count: number;
};

const initialState: CounterState = {
  count: 0
};

export default function counter(state = initialState, action: Action): CounterState {
  switch (action.type) {
    case TYPES.INCREMENT:
      return assign({}, state, {
        count: state.count + 1
      });
    case TYPES.DECREMENT:
      return assign({}, state, {
          count : state.count - 1
        });
    case TYPES.RESET:
      //error here
      return state.count=0;
    default:
      return state;
  }
}

I am using lodash's assign function. Thanks

Upvotes: 0

Views: 157

Answers (2)

Jeppe Stougaard
Jeppe Stougaard

Reputation: 422

You have specified the return type of your function as CounterState, but for the reset case, you are trying to return a number (state.count=0 evaluates to the number on the right, so you are returning 0)

Instead you should return a state object either using the initialState constant

case Types.RESET:
    return initialState;

Or using the assign as well here, if you have other properties on the state, you wish to preserve

case Types.RESET:
    return assign({}, state, {
      count : 0
    });

Upvotes: 3

Max Brodin
Max Brodin

Reputation: 3938

You function output parameter is CounterState, but you are trying to return a number here:

return state.count=0;

just replace it with

state.count = 0;
return state;

Upvotes: 0

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