The parameter 'any' cannot be assigned to the parameter 'never' - Array provided is incompatible

Question

The parameter 'any' cannot be assigned to the parameter 'never' - Array provided is incompatible

Currently delving into TypeScript and encountering an issue while setting a reducer in redux Toolkit. Here's the code snippet in question:

const testSlice = createSlice({
  name: "test",
  initialState: [],
  reducers: {
    callApi: (state, action) => {
      const getData = {
        type: "test/getData",
        data: action.payload
      };

      state.push(getData);
    }
  }
});

Observing that state.push(getData) is underlined in red within VSCode, displaying the error message:

Argument of type 'any' is not assignable to parameter of type 'never'

Attempted to declare const getData : any[] = {, but the same error persists.

Seeking guidance on identifying the mistake made. Appreciate any assistance!

typescript redux

Answer 1

Answer №1

The issue arises from assigning an empty array to initialState without specifying its type, causing TypeScript to infer the type as never[]

type CustomState = any[];

const initialState: CustomState = [];

const customSlice = createSlice({
  name: "custom",
  initialState,
  reducers: {
    fetchData: (state, action) => {
      const newData = {
        type: "custom/newData",
        data: action.payload
      };

      state.push(newData);
    }
  }
});

To address this issue, avoid using the any type if possible

Answer 2

The issue arises from assigning an empty array to initialState without specifying its type, causing TypeScript to infer the type as never[]

type CustomState = any[];

const initialState: CustomState = [];

const customSlice = createSlice({
  name: "custom",
  initialState,
  reducers: {
    fetchData: (state, action) => {
      const newData = {
        type: "custom/newData",
        data: action.payload
      };

      state.push(newData);
    }
  }
});

To address this issue, avoid using the any type if possible

The parameter 'any' cannot be assigned to the parameter 'never' - Array provided is incompatible

Answer №1

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