GeoJsonDataSource dataSourceDisplay.ready state

CesiumJS
1

Hello, we want to display our data on the map by using the method “Cesium.GeoJsonDataSource.load(data, options) → Promise.” in our project. But when we run this method in a loop, we cannot see it loading instantly. It expects all datasources to be loaded and dataSource sets Display.ready to false. What can I do so that the dataSourceDisplay.ready state is always true or that every data source I add appears instantly without waiting for the previous one?

My Code(result has list of url) :
for (let i = 0; i < result.length; i++) {
getGeoJsonData(result[i], onclick, layerName);
}

    function getGeoJsonData(geoJsonUrl, onclick, layerName) {
        let isFirstLoad = true;
        for (let i = 0; i < that.map3d.dataSources.length; i++) {
            if (that.map3d.dataSources._dataSources[i].name === geoJsonUrl) {
                isFirstLoad = false;
            }
        }

        if (!isFirstLoad)
            return;

        $.ajax({
            type: "GET",
            url: geoJsonUrl,
            success: function (data) {
                let promise = window.Cesium.GeoJsonDataSource.load(data);
                promise
                    .then(function (dataSource) { 
                        console.log(that.map3d.dataSourceDisplay.ready);
                        dataSource.name = geoJsonUrl;
                        dataSource.layerName = layerName; 
                        that.map3d.dataSources.add(dataSource);
                        const entities = dataSource.entities.values;
                        for (let i = 0; i < entities.length; i++) {
                            const entity = entities[i];
                            entity.oid = entity.properties.gd_id._value;
                            entity.description = entity.properties.gd_description._value;
                            entity.threeD = true; 
                            entity.onclick = onclick;
                            entity.polygon.material = entity.properties.gd_style._value;
                            entity.polygon.outline = false;
                            entity.polygon.extrudedHeight = entity.properties.gd_ext_height._value;
                        }
                    });  
            },
            error: function (e) {
                console.error("getobjects error: ", e);
            }
        });
    } 
};