我想循环在该州的数组中，并检查输入是否存在

发布于 2025-02-06 22:24:16 字数 874 浏览 1 评论 0原文

我尝试构建此方法addGamer（）检查游戏玩家数组中的用户名是否存在onclick添加按钮，如果他是，我希望它不会在数组中添加他的信息，我想知道为什么它为什么不添加工作？ ....我创建了此EnterData（）方法，以获取这三个游戏玩家信息的值

class App extends Component {
  state= {
    gamer:{
          FirstName:"",
          LastName: "",
          UserName: "",
    },
    gamers:[],
  }

  enterdata = (event)=> {
    const {name, value} = event.target;
    this.setState((prevstate)=>({
        gamer: {...prevstate.gamer,[name] : value},  
    }))
  }
  
  addgamer = (event) =>{
  event.preventDefault();
  for(let i = 0;i<this.state.gamers.length; i++){
    if(this.state.gamer.UserName === this.state.gamers[i].UserName){
        return false; 
    }else{
        this.setState(prevstate =>({
        gamers: [...prevstate.gamers, this.state.gamer],
        gamer: {FirstName:"", LastName: "", UserName: ""},
  }))
    }
  }  
  
  }

原文

I tried to build this method addgamer() to check if the username exists in the gamers array onClick add button and if he is , i want it don't add his info as an object in the array, i want to know why it didn't work ?
....i created this enterdata() method to get the values of these three gamer info onChange the values of their inputs

class App extends Component {
  state= {
    gamer:{
          FirstName:"",
          LastName: "",
          UserName: "",
    },
    gamers:[],
  }

  enterdata = (event)=> {
    const {name, value} = event.target;
    this.setState((prevstate)=>({
        gamer: {...prevstate.gamer,[name] : value},  
    }))
  }
  
  addgamer = (event) =>{
  event.preventDefault();
  for(let i = 0;i<this.state.gamers.length; i++){
    if(this.state.gamer.UserName === this.state.gamers[i].UserName){
        return false; 
    }else{
        this.setState(prevstate =>({
        gamers: [...prevstate.gamers, this.state.gamer],
        gamer: {FirstName:"", LastName: "", UserName: ""},
  }))
    }
  }  
  
  }

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故事与诗 2025-02-13 22:24:16

这里的问题是，您每次找不到用户名时都会添加游戏玩家。您应该做的是设置一个标志，以查看是否在游戏者列表中找到了用户名，然后然后 setState如果用户名是找不到，这样：

let found = false;
for(let i = 0;i<this.state.gamers.length; i++){
    if(this.state.gamer.UserName === this.state.gamers[i].UserName){
        found = true;
        break;
    }   
}
// alternatively: let found = this.state.gamers.find(gamer => this.state.gamer.UserName === gamer.UserName)
if (!found) {
    this.setState(prevstate =>({
        gamers: [...prevstate.gamers, this.state.gamer],
        gamer: {FirstName:"", LastName: "", UserName: ""},
    }))
}

The issue here is that you are adding the gamer every time the username is not found. What you should do is set a flag to see whether the username was found in the gamers list or not, and then do the setState to add the new gamer if the username was not found, like so:

let found = false;
for(let i = 0;i<this.state.gamers.length; i++){
    if(this.state.gamer.UserName === this.state.gamers[i].UserName){
        found = true;
        break;
    }   
}
// alternatively: let found = this.state.gamers.find(gamer => this.state.gamer.UserName === gamer.UserName)
if (!found) {
    this.setState(prevstate =>({
        gamers: [...prevstate.gamers, this.state.gamer],
        gamer: {FirstName:"", LastName: "", UserName: ""},
    }))
}

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