javascript - React component unmounted -

my react app routes so:

<route handler={routehandler}>     <route name="welcome" path="welcome" handler={welcomepage} />     <route name="app" path="/" handler={application}>         <route name="some-page" path="some-page" handler={somepage} />     </route> </route> 

the main "app" layout following

export default class application extends react.component {     render() {         return (<div>             <modalview />             <topbar />             <routehandler />         </div>);     } } 

the topbar giving me problems:

export default class topbar extends react.component {     componentdidmount() {         userstore.addchangelistener(this._onchange);     }     componentwillunmount() {         userstore.removechangelistener(this._onchange);     }     _onchange = () => {         this.setstate(this.getstate());     };     handleloginclick() {         actions.queuemodal("login");     }     handlesignupclick() {         actions.queuemodal("signup");     }     getstate() {         return {             currentuser: userstore.currentuser         };     }     state = this.getstate();     render() {         return (             <div classname="topbar">                 {this.state.currentuser ?                     (<link to="home"><button classname="default">{this.state.currentuser.email}</button></link>) :                     ([                         <button key={1} classname="clear" onclick={this.handlesignupclick}>sign up</button>,                         <button key={2} classname="clear" onclick={this.handleloginclick}>log in</button>                     ])}             </div>         );     } } 

according "app" layout, topbar should mounted when in some-page. when complete login, userstore emits change, received topbar. instead of bar updating itself, error message "warning: setstate(...): can update mounted or mounting component. means called setstate() on unmounted component. no-op." why this?

it dont have initial state component topbar. try set intial state in contructor .

   constructor(props) {         super(props);         this.state = {name: props.name};     }