使用地图时反应'无法读取未定义的属性'

您尚未绑定要使用的map函数

onScoreChange = {this.onPlayerScoreChange}

您可以使用绑定或箭头功能进行绑定

需要PS绑定，因为map函数的上下文不同于React Component上下文，因此

this

this

具有箭头功能：

 {this.state.initialPlayers.map((player, index)=> {     return(         <Player          name = {player.name}          score = {player.score}          key = {player.id}          index = {index}         onScoreChange = {this.onPlayerScoreChange}         />     ) })}

带绑定

   {this.state.initialPlayers.map(function(player, index) {     return(         <Player          name = {player.name}          score = {player.score}          key = {player.id}          index = {index}         onScoreChange = {this.onPlayerScoreChange}         />     ) }.bind(this))}