在 jsx 和 map 中响应 if 语句

Question

i have working code and little problem with if statement in map function here is code

    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>
  );
});

now i want chceck if statement to render only when in map cashitem has state is visible cashitems isVisible already have isVisible:true or false i want to do something like that

 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
          ... 
        />)
        
      }
    }

Instead of using parenthesis, change it to curly braces and using a return keyword withint the if else condition as above

Answer 2

You aren't returning the component inside your if statement.

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

However since you are filtering your list, why not use the Array.filter method?

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

Answer 3

An arrow function which consists of more than a single expression needs:

• Braces around it
• An explicit return statement

Thus:

(cashitem, index) => {
    if (condition) {
        return <Component />
    }
}

Answer 4

Create a function that handle the if/else statement and return the jsx/html builder, then call it in the jsx render() function.

Check this solution / author: Blair Anderson

renderSkillSection: function(){
  if (this.state.challengeChoices.length < 0) {                               
    return this.state.challengeChoices.map((para2, i) =>
         <ChallengeSkill key={i} {...para2} callback={this.madeSelection} />)
  }
  else {
    return <div>Hello world</div>
  }   
},

render: function(){
 return (<div className="skillSection">
  {this.renderSkillSection()}   
 </div>)
}