Question

如何检查ticketId是否已插入数组？

这是代码：

state = { myState: [], status: 0, limit: 5 };

  selected(ticketId) {
  if (this.state.status < this.state.limit) { 
    this.state.myState.push({ id: ticketId }); //what ever i chose get inserted
    this.state.status++;
    this.setState({ status: this.state.status }); 
    //console.log('here', this.state.status);
  } else {
    console.log('3'); //check if condition meet
  }
 }

如果myState已插入并触发警报，如何创建检查ticketId数组的条件？

Answer 1

您好，您可以使用 loadash Find it Here来解决这类问题，简单而且非常好看！：）

示例1

_.indexOf([1, 2, 1, 2], 2); // => 1

或者您可以使用

示例2

var users = [ { 'user': 'barney', 'active': false }, { 'user': 'fred', 'active': false }, { 'user': 'pebbles', 'active': true } ]; _.findIndex(users, function(o) { return o.user == 'barney'; }); // => 0 // The `_.matches` iteratee shorthand. _.findIndex(users, { 'user': 'fred', 'active': false }); // => 1 // The `_.matchesProperty` iteratee shorthand. _.findIndex(users, ['active', false]); // => 0 // The `_.property` iteratee shorthand. _.findIndex(users, 'active'); // => 2

在您的代码中

_.findIndex(this.state.myState, { 'id': ticketId }); // It will return 0 if there is nothing // else will return no of index // where it ticketid is present // you can do alert on if its not 0

Answer 2

当您作为对象{id：value}存储时，最好使用“every”。

state = { myState: [], status: 0, limit: 5 };

selected(ticketId) {
   if (this.state.status < this.state.limit ) { 
      if(this.state.myState.every((item) => item.id !== ticketId)){
        this.state.myState.push({ id: ticketId }); //what ever i chose get inserted
        this.state.status++;
        this.setState({ status: this.state.status }); 
      //console.log('here', this.state.status);
     }
   } else {
   console.log('3'); //check if condition meet
   } 
}

React-native数组检查值是否存在

2 个答案: