Use window.open():
Share Page
This will create a link titled Share Page which opens the current url in a new window with a height of 570 and width of 520.
Just use window.open() function? The third parameter lets you specify window size.
Example
var strWindowFeatures = “location=yes,height=570,width=520,scrollbars=yes,status=yes”;
var URL = “https://www.linkedin.com/cws/share?mini=true&url=” + location.href;
var win = window.open(URL, “_blank”, strWindowFeatures);