如何从XMLHttpRequest响应中按类名过滤元素？ [重复]

I'm working on a dynamic navigation bar that uses the XMLHttpRequest function in vanilla JS to get content a certain div class from a link within the site. I'm currently trying to figure out how to only filter out a div with class pageInner from response variable resp, like how find() is used to filter elements by class name from an AJAX response variable in jQuery.

JS：

var request = new XMLHttpRequest();
request.open('GET', this.href, true);

request.onload = function() {
      if (this.status >= 200 && this.status < 400) {
      var resp = this.response;

      document.querySelector('.pageInner').innerHTML = resp.querySelectorAll('.pageInner')[0]; \\ incorrect code
}
};

request.send();