Enable to display many digits on clicked button on the screen of my reactjs calculator-CodePudding

i don't know why when i click on DigitButton the calculator disappeare like there is a bug. I know the problem is on the curerentOperation property side but I actually don't know which problem it is. When i remove the currentOperation and previousOperator in the backticks each digit is rendered.

here is the linkto my Pen

CodePudding user response：

In your reducer you need to get access to previousOperation using state.previousOperation

const reducer = (state, { type, payload }) => {
  switch (type) {
    case ACTIONS.ADD_DIGIT:
      return {
        ...state,
        previousOperation: `${""}${payload.digit}`,
        currentOperation: `${""}${payload.digit}`
      };
    case ACTIONS.CLEAN:
      return {};
    case ACTIONS.ADD_OPERATOR:
      return {
        ...state,
        // Line: 43
        previousOperation: `${state.previousOperation || ""}${payload.operator}`
      };
  }
};