javascript regexp replace not working, but string replace works

I'm working with jQuery and am trying to write a pattern replace, but it doesn't work. I have this:

var $featured_rewrite = $('#featured').not('.slideshow');
$featured_rewrite.children().attr('href', $featured_rewrite.find('img').attr('src').replace('/-开发者_运维技巧[0-9]+x[0-9]+\./i', '.'));

I don't understand why something like this works:

.replace('-500x277.', '.')

but not this, which I even checked with a tool and made sure it was valid and works:

.replace('/-[0-9]+x[0-9]+\./i', '.')

'/-[0-9]+x[0-9]+\./i' is a string.

/-[0-9]+x[0-9]+\./i is regex.

"hi".match('/hi/')  // returns null
"hi".match(/hi/)    // returns ["hi"]

Edit: Also, just to be clear, there's nothing wrong with your regex other than the quotes. You may want to consider using /g (i.e. /gi at the end) if you need to replace more than one match, but that's it.