How to check value is empty, or null in JavaScript?

Question

I have a problem when I wanna get data from state, in console.log appears 2 values. I want remove the empty value, but I've run out of ways. How to remove an empty value?

class DetailOrderTracking extends Component {
    constructor(props) {
        super(props)
        this.state = {
            data: []
        }
    }

    componentDidMount = async () => {
        const { query } = this.props.router;
        var getOrderTrackings = await OrderTrackingRepository.getOrderTracking(query.numberbill, query.courier);
        if (getOrderTrackings.ordertracking.status.code == 200) {
            var getManifest = getOrderTrackings.ordertracking.result.manifest;
            this.setState({ data: getManifest });
        }
    }

    render() {
        const { data } = this.state;
        console.log(data) // will print 2 values, first condition is empty value, and second condition has values (an example is in the image above)
        return (
            <div/>
        )
    }
}

check the length of the data array --> data.length. If its zero, array is empty. — Yousaf
– Yousaf, Commented Sep 18, 2020 at 15:41
What does that mean, you "want to remove the empty value"? Your component starts out with empty data, and render is called. Then you populate the data, and render is called again at that point… — deceze
– deceze ♦, Commented Sep 18, 2020 at 15:42
If you are using lodash, you have a method called isEmpty to check or the best way to determine whether the array is empty or not is by the length. — arunmmanoharan
– arunmmanoharan, Commented Sep 18, 2020 at 15:45

daniloxxv · Accepted Answer · 2020-09-18 15:43:25Z

2

This should do it:

    render() {
        const { data } = this.state;
        if (data.length > 0){
          console.log(data)
        }
        return (
            <div/>
        )
    }

answered Sep 18, 2020 at 15:43

daniloxxv

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