[Nexus]

Попробуйте так:

xhr(adress).then(response=>console.log(response));

function xhr(adress) {

    const request = (resp) => {
        // console.log(resp); // {"response":{"GeoObjectCollection": ...
        let obj = JSON.parse(resp); // конвертируем из json в объект js // 
        obj = obj.response; // {GeoObjectCollection: {…}}
        obj = obj.GeoObjectCollection; // {metaDataProperty: {…}, featureMember: Array(1)}
        obj = obj.featureMember[0]; // GeoObject: {metaDataProperty: {…}, boundedBy: {…}, Point: {…}}
        obj = obj.GeoObject.Point; // {pos: "37.620555 55.741333"}
        const coords = obj.pos; // 37.620555 55.741333
        return coords;
    }

    function httpGet(fullUrl) {
      return new Promise(resolve=>{
        const xhr = new XMLHttpRequest();
        xhr.open("GET", fullUrl, true);
        xhr.onload=()=>{
          resolve(
          	request(xhr.responseText)
          );
        };
        xhr.send();
        
      });
    }

    const url = 'https://geocode-maps.yandex.ru/1.x/?';
    const apikey = 'xxx&format=json&geocode=';
    const fullUrl = url + apikey + adress;

    return httpGet(fullUrl);
}