javascript - React Native，如何将嵌套的if else转换为switch语句？

Question

嘿，我是 react-redux 的新手，我正在努力将嵌套的 if else 语句转换为 switch 语句。谁能告诉我该怎么做？下面是我的代码

if (action.type === ADD_TO_CART) {
    let addedItem = state.jeans.find((item) => item.id === action.id);
    let existed_item = state.addedItems.find((item) => action.id === item.id);
    if (existed_item) {
      addedItem.quantity += 1;
      return {
        ...state.jeans,
        total: state.total + addedItem.price,
      };
    } else {
      addedItem.quantity = 1;
      let newTotal = state.total + addedItem.price;

      return {
        ...state,
        addedItems: [...state.addedItems, addedItem],
        total: newTotal,
      };
    }
  }

Answer 1

我猜你只是想把它从 if else 切换到 switch 对吗？

在这种情况下，我猜您可以执行以下操作:

if (action.type === ADD_TO_CART) {
    let addedItem = state.jeans.find((item) => item.id === action.id);
    let existed_item = state.addedItems.find((item) => action.id === item.id);
    switch(existed_item){
        case !undefined: {
            addedItem.quantity += 1;
            return {
              ...state.jeans,
              total: state.total + addedItem.price,
            };
        }
        default: {
            addedItem.quantity = 1;
            let newTotal = state.total + addedItem.price;
        
            return {
              ...state,
              addedItems: [...state.addedItems, addedItem],
              total: newTotal,
            };
        }
    }
}