code: function captureImage(page) {
          if (DEBUG && !page.phantom) inspectArgs("captureImage: ", page);
  
          if (option.selector) {
              let getElement = [ "function () {",
                  , "document.body.bgColor = 'white';"
                  , `var elem = document.querySelector('${option.selector}');`
                  , "return (elem !== null) ? elem.getBoundingClientRect() : null; };"
              ].join("");
  
              return page.evaluateJavaScript(getElement);
          }
      }
docs: Capture the specified image.