在 jsx 和 map 中响应 if 语句

Question

我有工作代码，并且 map 函数中的 if 语句没有什么问题，这里是代码

    const SortableItem = SortableElement(CashItem);
const SortableList = SortableContainer(({items}) => {
  return (
    <div>
      {items.map((cashitem, index) => (
        <SortableItem key={`item-${index}`} 
          index={index} 
          isPayed={cashitem.isPayed}
          date={cashitem.date}
          name={cashitem.name}
          realisticVal={cashitem.realisticVal}
          realisticBalance={cashitem.realisticBalance}
          optimisticBalance={cashitem.optimisticBalance}
          optimisticVal={cashitem.optimisticVal}
          changedName={(event) => this.nameChangedHandler(event, cashitem.id)} 
          isBlocked={(event) => this.handleChangeCheckbox(event, cashitem.id)} 
          delete={(event) => this.removeItem(event, cashitem.id)} 
          addNext={(event) => this.addNext(event, cashitem)} 
          realisticChange={(event) => this.realisticBalanceChangedHandler(event, cashitem.id)}  
          optimisticChange={(event) => this.optimisticBalanceChangedHandler(event, cashitem.id)}  
          dateChangedHandler={(event) => this.dateChangedHandler(event, cashitem.id)}
         />
      ))}
    </div>
  );
});

现在我想要检查 if 语句仅在地图中的 cashitem 有状态可见时才呈现 cashitems isVisible 已经有 isVisible:true 或 false 我想做类似的事情

 const SortableItem = SortableElement(CashItem);
const SortableList = SortableContainer(({items}) => {
  return (
    <div>
      {items.map((cashitem, index) => (
        if(cashitem.isVisible===true){
          <SortableItem key={`item-${index}`} 
          index={index} 
          isPayed={cashitem.isPayed}
          date={cashitem.date}
          name={cashitem.name}
          realisticVal={cashitem.realisticVal}
          realisticBalance={cashitem.realisticBalance}
          optimisticBalance={cashitem.optimisticBalance}
          optimisticVal={cashitem.optimisticVal}
          changedName={(event) => this.nameChangedHandler(event, cashitem.id)} 
          isBlocked={(event) => this.handleChangeCheckbox(event, cashitem.id)} 
          delete={(event) => this.removeItem(event, cashitem.id)} 
          addNext={(event) => this.addNext(event, cashitem)} 
          realisticChange={(event) => this.realisticBalanceChangedHandler(event, cashitem.id)}  
          optimisticChange={(event) => this.optimisticBalanceChangedHandler(event, cashitem.id)}  
          dateChangedHandler={(event) => this.dateChangedHandler(event, cashitem.id)}
         />
        }

      ))}
    </div>
  );
});

Answer 1

{
     items.map((cashitem, index) => { //<== change it to curly braces

        return cashitem.isVisible && (<SortableItem key={`item-${index}`} //<== using the return keyword
          ... 
        />)
        
      }
    }

不要使用括号，而是将其更改为花括号，并return在 if else 条件中使用关键字，如上所述

Answer 2

您没有在 if 语句中返回组件。

{items.map((cashitem, index) => {
    if(cashitem.isVisible){
        return <SortableItem key={`item-${index}`} ...otherProps/>
    }
})}

但是，既然您正在过滤列表，为什么不使用Array.filter方法呢？

{items.filter(cashItem => cashItem.isVisible).map((cashitem, index) => (
    <SortableItem key={`item-${index}`} ...otherProps/>
)}