We have recently benefited from using knockout.js to add richness to some of our web application forms. Once our view model is bound, the library allows us to update text on the form dynamically and easily. Naturally, it wasn’t long before someone asked, “How do I format money using knockout.js?” Some folks had some partial answers and some folks had some answers that didn’t work. It was particularly challenging to deal with users selecting partial fields, negative amounts, and what not, so we rolled our own knockout extension. We wouldn’t say our answer is perfect, but we think it is a fair compromise that works with the major browsers. Behold, the jsFiddle for money formatting in knockout.