react component error Cannot read property of undefined

Question

i am new to React i created component like this ;

export default class CartoviewDrawer extends React.Component {

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

    _handleToggle() {
        let open = this.state.open;
        this.setState({open: !open})
    }

    render() {
        return (
            <div>
                {/*<RaisedButton*/}
                {/*label="Toggle Drawer"*/}
                {/*onTouchTap={this.handleToggle}*/}
                {/*/>*/}
                <IconButton tooltip="Toggle Drawer"
                            onTouchTap={this._handleToggle}
                >
                    <i className="material-icons">list</i>
                </IconButton>
                <IconButton iconClassName="muidocs-icon-custom-github"/>
                <Drawer open={this.state.open}>
                    <MenuItem>Menu Item</MenuItem>
                    <MenuItem>Menu Item 2</MenuItem>
                </Drawer>
            </div>
        );
    }
}

and in another file i import this component by ;

import CartoviewDrawer from './cartoview_drawer'

then i use this component :

React.createElement(AppBar,toolbarOptions,React.createElement(CartoviewDrawer))

but when i click on the icon error in browser console and drawer not appear. error:

Uncaught TypeError: Cannot read property 'open' of undefined

Answer 1

You are missing the binding to 'this' change the onTouchTap call to this:

onTouchTap={this._handleToggle.bind(this)}

Answer 2

Add binding in component's contructor:

constructor(props) {
  super(props);
  ...
  this._handleToggle= this._handleToggle.bind(this);
}