gistfile1.js

function GW2TESTING(){
  var myUrl = "http://www.gw2spidy.com/api/v0.9/json/all-items/*all*";
  var jsonData = UrlFetchApp.fetch(myUrl);
  var jsonString = jsonData.getContentText();
    
  jsonString.replace(/\\n/g, "\\n");
  jsonString.replace(/\\'/g, "\\'");
  jsonString.replace(/\\"/g, '\\"');
  jsonString.replace(/\\&/g, "\\&");
  jsonString.replace(/\\r/g, "\\r");
  jsonString.replace(/\\t/g, "\\t");
  jsonString.replace(/\\b/g, "\\b");
  jsonString.replace(/\\f/g, "\\f");
           
  //jsonString = jsonString.escape();
  
  var jsonObject = JSON.parse(jsonString);
  
  //Controll value
  return jsonObject.count;
}

Error in line 17