reactjs using async server calls

api.ts

class Api {
    ...

    async getEntitledForA() {
        try {
            const orgsResponse = await fetch('/api/v1/orgs');
            const orgResponseJson = await orgsResponse.json();
            return orgResponseJson.data;
        } catch (err) {
            console.error(err);
            return null;
        }
    }

    async getEntitledSites(orgId: number) {
        try {
            const sitesResponse = await fetch('/api/v1/study/' + orgId + '/sites');
            const sitesResponseJson = await sitesResponse.json();
            return sitesResponseJson;
        } catch (err) {
            console.error(err);
            return null;
        }
    }
}

export default new Api();

CreateDashboard.jsx

import React, {Component} from 'react';
import SelectDropDownA from '../components/SelectDropDownA';
import SelectDropDownB from '../components/SelectDropDownB';
import SelectDropDownC from '../components/SelectDropDownC';

class CreateDashboard extends Component {
    constructor() {
        super();

        this.state = {
            organizations: [],
            sites: [],
            selectedAId: "0",
            selectedBId: "0",
            selectedCId: "0",
            showBMenu: false
        }
        
    }

    async componentDidMount() {
        let organizations = await Api.getEntitledForA();
        this.setState({ organizations });
    }

    async onSelectedOrgChange(selectedOrgId) {
        if (selectedOrgId !== 0) { 
            this.setState({ selectedAId });
            let sitesData = await Api.getEntitledSites(this.state.selectedAId);
            this.setState({ 
                sites: sitesData.sites,
                showSitesMenu: true
            });
        }
    }

    ...


    render() {
        return (
            <div className="panel">
                <div className="insidePanel">
                    <SelectStudyDropDown 
                        onChange={e => this.onSelectedOrgChange(e.target.value)}
                        ...
                    />
                </div>
                {this.showSitesMenu && 
                    <div className="insidePanel">
                        <SelectSiteDropDown
                            onChange={e => this.onSelectedSiteChange(e.target.value)}
                            ...
                        />
                    </div>
                }
            </div>
        )
    }
}

export default CreateDashboard;