Open URL in same window and in same tab
You need to use the name attribute:
window.open("https://www.youraddress.com","_self")
Edit: Url should be prepended with protocol. Without it tries to open relative url. Tested in Chrome 59, Firefox 54 and IE 11.
In order to ensure that the link is opened in the same tab, you should use window.location.replace()
See the example below:
window.location.replace("http://www.w3schools.com");