javascript window.location in new tab

This works for me on Chrome 53. Haven't tested anywhere else:

function navigate(href, newTab) {
   var a = document.createElement('a');
   a.href = href;
   if (newTab) {
      a.setAttribute('target', '_blank');
   }
   a.click();
}

I don't think there's a way to do this, unless you're writing a browser extension. You could try using window.open and hoping that the user has their browser set to open new windows in new tabs.

You can even use

window.open('https://support.wwf.org.uk', "_blank") || window.location.replace('https://support.wwf.org.uk');

This will open it on the same tab if the pop-up is blocked.

window.open('https://support.wwf.org.uk', '_blank');

The second parameter is what makes it open in a new window. Don't forget to read Jakob Nielsen's informative article :)