Please document how to reference a list of items

Please document how to use forwardRef (the preferred way) to retrieve a list or array of items. For example,

const foo = React.forwardRef( (props,ref) => 
  props.superHeros.map( 
    ( hero, index) => <li ref={  ref  } key={ index }>{ hero }</li>
  ) 
)

Perhaps the key question here is, why not do this?

componentDidMount(){
  const foo = this.refs.root.querySelector('.foo')
  ...
}

Suppose there are 50,000 className='foo' elements that are returned by an embedded component. Is this code not portable? Is this code slower than having 50,000 ref created?

Please document this.

從 issue 中的 forwardRef 範例開始，並將其與 componentDidMount/querySelector 方法進行比較。記錄如何參照項目清單或陣列，包括針對許多元素所提出的可攜性與效能問題。當首選方法及其取捨獲得清楚說明時，即視為完成。