Communicate Asynchronous Loading End To React Interface

There is a class called JSONHeader which server us to load each one of the JSONs:

import jQuery from 'jquery-ajax';
import Atlas from "./Atlas";

export default class JSONHeader {
    constructor(location) {
        loadAtlasStructure(location);

        function loadAtlasStructure(location) {
            jQuery.ajax({
                dataType: "json",
                url: location,
                async: true,
                success: function (files) {
                    files.map((file) => {
                        jQuery.ajax({
                            dataType: "json",
                            url: location + file,
                            async: true,
                            success: function (data) {
                                console.log(data);
                                if (!window.IndexAtlas) {
                                    window.IndexAtlas = new Atlas();
                                }
                                window.IndexAtlas.addSubAtlas(data);
                                console.log('JSONHeader::window.IndexAtlas', window.IndexAtlas);
                            }
                        });
                    })
                }
            })
        }
    }
}

And I would like to change the React's top level component: App, from isLoading: true, to isLoading: false, after all json have been loaded. How could we achieve that behaviour?. Currently I am forcing to wait 5 seconds each time we reload all JSONs

import React, {Component} from 'react';
import BrowserRouter from "react-router-dom/es/BrowserRouter";
import Switch from "react-router-dom/es/Switch";
import Route from "react-router-dom/es/Route";
import Redirect from "react-router-dom/es/Redirect";
import ScenePage from "../ScenePage/index";
import CoverPage from "../CoverPage/index";
import {INDEX, SCENE_PAGE} from "../../constantRoutes";
import JSONHeader from "../../newModel14Junio/JSONHeader";

export default class App extends Component {
    constructor(props) {
        super(props);

        const header = new JSONHeader('/atlas/json/');

        this.state = {
            isAtlasLoading: true
        };

        setTimeout(() => {
            this.setState({isAtlasLoading: false});
        }, 5000);
    }

    render() {
        if (this.state.isAtlasLoading) {
            return (<div>Atlas loading</div>);
        }
        return (
            <BrowserRouter>
                <div>
                    <Switch>
                        <Route exact path={INDEX} component={CoverPage}/>
                        <Route path={SCENE_PAGE} component={() => <ScenePage IndexAtlas={window.IndexAtlas}/>}/>
                        <Redirect from="*" to={INDEX}/>
                    </Switch>
                </div>
            </BrowserRouter>
        );
    }
}

Thank you for your help.

It's not a good idea to use timeout to do that, because you don't know how much time it will spend to finish. So, you can add a callback to your JSONHeader, like that:

import jQuery from 'jquery-ajax';
import Atlas from "./Atlas";

export default class JSONHeader {
    constructor(location, callback) {
        loadAtlasStructure(location);

        function loadAtlasStructure(location, callback) {
            jQuery.ajax({
                dataType: "json",
                url: location,
                async: true,
                success: function (files) {
                    files.map((file) => {
                        jQuery.ajax({
                            dataType: "json",
                            url: location + file,
                            async: true,
                            success: function (data) {
                                console.log(data);
                                if (!window.IndexAtlas) {
                                    window.IndexAtlas = new Atlas();
                                }
                                window.IndexAtlas.addSubAtlas(data);
                                console.log('JSONHeader::window.IndexAtlas', window.IndexAtlas);
                                callback();
                            }
                        });
                    })
                }
            })
        }
    }
}

In your ReactJS, you just create a callback and pass it when you call JSONHeader:

import React, {Component} from 'react';
import BrowserRouter from "react-router-dom/es/BrowserRouter";
import Switch from "react-router-dom/es/Switch";
import Route from "react-router-dom/es/Route";
import Redirect from "react-router-dom/es/Redirect";
import ScenePage from "../ScenePage/index";
import CoverPage from "../CoverPage/index";
import {INDEX, SCENE_PAGE} from "../../constantRoutes";
import JSONHeader from "../../newModel14Junio/JSONHeader";

export default class App extends Component {
    constructor(props) {
        super(props);

        const finishCallback = () => {
            this.setState({isAtlasLoading: false});
        };

        const header = new JSONHeader('/atlas/json/', finishCallback);

        this.state = {
            isAtlasLoading: true
        };        
    }

    render() {
        if (this.state.isAtlasLoading) {
            return (<div>Atlas loading</div>);
        }
        return (
            <BrowserRouter>
                <div>
                    <Switch>
                        <Route exact path={INDEX} component={CoverPage}/>
                        <Route path={SCENE_PAGE} component={() => <ScenePage IndexAtlas={window.IndexAtlas}/>}/>
                        <Redirect from="*" to={INDEX}/>
                    </Switch>
                </div>
            </BrowserRouter>
        );
    }
}

I hope that I helped you.