'function' is not defined within React Component

Question

I'm very new to working with react so I tried to create a small timer application, but I receive the following error when I run this code:
(Line 40: 'timeDisplay' is not defined no-undef)

class Home extends React.Component {
    constructor(props) {
        super(props);


        // Four states:
        // work , workStop, break, breakStop

        this.state = {
            status: 'workStop',
            time: 1500
        }
    }

    componentDidMount() {
        var interval = setInterval(this.timeTick, 1000);
        this.setState({interval});
    }

    componentWillUnmount() {
        clearInterval(this.state.interval);
    }

    timeTick = () => {
        if (this.state.time !== 0)
            this.setState({
                time: this.state.time - 1
            });
    }

    timeDisplay = () => {
        const minute = Math.floor(this.state.time / 60);
        const second = (this.state.time % 60) < 10 ? '0' + (this.state.time % 60) : (this.state.time % 60);
        return (minute + ' : ' + second);
    }

    render() {
        const time = timeDisplay();
        return (
            <div>
                <p className='timer'>{time}</p>
            </div>
        )
    }
}

Not sure what to do in this situation, I used the arrow function for defining the timeDisplay method inside the component.

Change the following line to: const time = this.timeDisplay();. — Sotiris Kiritsis
– Sotiris Kiritsis, Commented Jun 15, 2017 at 7:11

I Putu Yoga Permana · Accepted Answer · 2017-06-15 07:16:39Z

10

Well timeDisplay is member of instance of Home component. You need this to access that function. Therefore using :

const time = this.timeDisplay();

is the correct one instead

const time = timeDisplay();

answered Jun 15, 2017 at 7:16

I Putu Yoga Permana

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Comments

codejockie · Accepted Answer · 2017-09-03 01:14:05Z

1

To access an instance method in a class always use this.

answered Sep 3, 2017 at 1:14

codejockie

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