Does not work with latest jQuery (Solution provided)

I get this error:

Uncaught Syntax error, unrecognized expression: [href$=.mp3]

“cybacolt” has already shown that this can be fixed by changing the JS from:

jQuery('a[href$=.mp3]').addClass('wpaudio');

To:

jQuery('a[href$=mp3]').addClass('wpaudio');

However, the real issue here is that “.mp3” is supposed to be quoted, according to https://api.jquery.com/attribute-ends-with-selector/ (“Quotes are mandatory”).

But there’s a second, more subtle issue: “The comparison is case sensitive.” — this means a link ending in “.MP3” will be ignored. So here’s a more comprehensive fix:

jQuery("a").filter(function(){ return /\.mp3$/i.test($(this).attr("href")); })