code: function() {
      var jsPath, scripts, i;
      if (_document.currentScript && (jsPath = _document.currentScript.src)) {
        return jsPath;
      }
      scripts = _document.getElementsByTagName("script");
      if (scripts.length === 1) {
        return scripts[0].src || undefined;
      }
      if ("readyState" in (scripts[0] || document.createElement("script"))) {
        for (i = scripts.length; i--; ) {
          if (scripts[i].readyState === "interactive" && (jsPath = scripts[i].src)) {
            return jsPath;
          }
        }
      }
      if (_document.readyState === "loading" && (jsPath = scripts[scripts.length - 1].src)) {
        return jsPath;
      }
      if (jsPath = _getCurrentScriptUrlFromError()) {
        return jsPath;
      }
      return undefined;
    }
docs: Get the current script's URL.
  
  @returns String or `undefined`
  @private