Want to achieve web page timing become focus execution

This button page implements "window.open()" to open a new window.
I would like to ask how I can automatically bring the button page to focus if I am browsing another page and the button page is not closed. I don't want to use "window.open" again to bring the button page to focus.
Before, I tried to execute a certain page in the background, and then I wanted to use the "window.location.href" to a page that open a new window of the button page after a period of time, so that the button page becomes the focus of execution, but I failed.
Later I tried a page in the background using "window.location.href" to jump to the button page then the button page automatically become the focus, but failed!
Because I am new for js, trouble a little more detailed, please help me! Thank you very much!