javascript - 如何在循环中推送对象数组中的值？

Question

如何在循环中将数组推送到处于 react 状态的对象列表中？

我的默认状态:

this.state = {
            users: [
                {
                    id:1,
                    name: 'John'
                },
                {
                    id:2,
                    name: 'Nick'
                }
            ]
        };

我尝试过类似的方法，但不起作用

changeHandler (currentUser, newValue) {
        const users = this.state.users;
        for (var i in users) {
            if (users[i].id == currentUser) {
                this.setState({
                    users: [...this.state.users[i], {newValue: newValue}]
                })
            }
            break;
        }
    }

所以我希望看到:

default state - {id:1,name: 'John'},{id:2, name: 'Nick'} 
use changeHandler(2,1) - {id:1,name: 'John'},{id:2, name: 'Nick', newValue: [1]}
use changeHandler(2,2) - {id:1,name: 'John'},{id:2, name: 'Nick', newValue: [1,2]}
use changeHandler(2,3) - {id:1,name: 'John'},{id:2, name: 'Nick', newValue: [1,2,3]}

Answer 1

您可以使用扩展语法来映射和更新状态，例如

changeHandler (currentUser, newValue) {
    const users = this.state.users;
    this.setState(prevState => ({
       users: prevState.users.map((user => {
           if (user.id == currentUser) {
              return {
                  ...user,
                  newValue: [...(user.newValue || []), newValue]
              }
           }
           return user
       }))
    }))
}