Edit in JSFiddle

Result
JavaScript
CSS
HTML

//rel="external"のあるa要素
$("a[rel*='external']").each(function(){
    //a要素にtarget="_blank"の追加やtitle属性など変更を加える
    $(this).attr({
        target:"_blank",
        title: ($(this).attr("title")) ? "New window: " + $(this).attr("title") : "Open in new window"
    });
});

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