gistfile1.txt

  let mdnRequest = require("sdk/request").Request({
    url: "https://developer.mozilla.org/en-US/search.json?q=" + currentCssProperty + "&topic=css",
    onComplete: showTheDocSummary
  });
  mdnRequest.get();
  
  ...
  
  
  function showTheDocSummary(response) {
  if (response.status == 200) {
    let json = response.json;
    let excerpt = json.documents[0].excerpt;
    let docURL = json.documents[0].url;
  }
}