我正在尝试设置 reactjs State 动态值

Question

I have defined an array which contains state properties. I am checking each state property by looping through array if its empty then picking the current iteration item and getting the state value through this iteration variable but it give undefined ie this.state.item is undefined and setting pass_msg state property accordingly?My state is

 this.state={
    old_pass:'',
    conf_pass:'',
    new_pass:'',
    pass_msg:''
}

update_password=(e)=>{
    let checks=["old_pass","new_pass","conf_pass"];
    checks.forEach(item=>{
    // give value  
    console.log('item',item)
    // but this is undefined .problem is here
    console.log('item',this.state.item)
    if(this.state.item === ''){
      this.setState({pass_msg:item+"is required"});
      return;
    }
})

}

Answer 1

The reason this.state.item is undefined is because the state does not have a property item. If you want to use a variable as a key to get the property from the state, you will need to get it like this:

this.state[item]