open() method has the first argument will be URL which you want to open
and the second argument will be the option which decides
window.open("http://www.google.com","_blank");
it will open the new tab or window with the given first argument URL, so it open http://www.google.com in the new tab or window
window.open("http://www.google.com","_self");
it will open in the same tab or window for the given URL as the first argument, it means http://www.google.com in the current tab or window
window.open("http://www.google.com","_parent");
if you running in iframe this code , it will open the http://www.google.com in parent window which host iframe
if still it runs in the parent window, it will work as _self , it will open given url in the current tab or window
window.open("http://www.google.com","_top");
in frameset , one of the child if run above code , it will open given url in the first parent
window.open("https://www.google.com", "", "width=400,height=400");
it open window with height and width 400 , with given url
window.open("", "", "width=400,height=400");
it open blank window with height and width 400
window.open("https://www.google.com", "_blank", "toolbar=yes,scrollbars=yes,resizable=yes,top=200,left=200,width=200,height=200");
we can control the window as many by above parameter ,