W3School TIY Editor
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<!DOCTYPE html> <html> <head> <style> div { width:70px; height:70px; background:#abc; border:2px solid black; margin:10px; float:left; } div.before { border-color: red; } </style> <script type="text/javascript" src="/jquery/jquery.js"></script> </head> <body> <div></div> <div></div> <div></div> <div></div> <script>$("div:last").prevAll().addClass("before");</script> </body> </html>