Make Safari bookmark open in a new tab by default
Over the years, there have been several questions regarding how to make Safari open a bookmark (for example, a Favorite) in a new tab by default (that is, without using the command key). There doesn't seem to have been any solution posted.
One way to do it is to manually edit each bookmark you want to open by default in a new tab so that its URL is embedded in a bit of Javascript. The Javascript template I use is this:
javascript:function%20openInNewTab(url)%20{var%20win%20=%20window.open(url,%20'_ blank');win.focus();};openInNewTab("PUT_YOUR_URL_HERE")
This code defines a small function to open a URL in a new tab, then calls the function with the given URL.
The way I set it up is to save the bookmark as usual, then copy everything in the above code through the first doublequote into the paste buffer. Then I Edit Bookmarks, and paste the copied material as a prefix to the left of the bookmark's URL. Then I type the ") on the right.
It's kind of painful to do the editing, but the method does appear to work. There may be some way to automate the editing, but I don't know what it is.
MacBook Pro (Retina, 15-inch, Mid 2014), macOS Sierra (10.12.4)