Is it possible to make links open in a new tab by default? I have a website where by default I would like all external links to have the "open in a new tab" option to be selected by default. I'm wondering if this is possible either through craft or redactor? I came across this but think it may be overkill so I'm wondering if its possible without a plugin.
Merits of doing this aside, I agree that JS is probably the easiest way to go here.

This code adds target="_blank" to all external links. 

// Make sure any offsite links (non js/mailtos) open in a new window
// from https://css-tricks.com/snippets/jquery/open-external-links-in-new-window/ - comment at end.
function openAllExternalLinksInANewWindow() {
    $(document).on('mousedown', 'a:not([href*="mailto:"],[href*="javascript"])', function(e) {
        var isInternalLink = new RegExp('/' + window.location.host + '/');
        if (!isInternalLink.test(this.href)) {
            $(this).attr('target', '_blank');
        }
    });
}