Five years ago, this was definitely true; however, I've had pretty good luck lately writing code in Chrome that works equally well in Firefox or IE9 without any

Five years ago, this was definitely true; however, I've had pretty good luck lately writing code in Chrome that works equally well in Firefox or IE9 without any additional effort on my part. I'm a pure JS guy. I used to do a lot of work in Flash, and one of the nicest parts was knowing that what you write works as intended across environments. One of the nice side-effects of the HTML5 mob is that the browser vendors are putting a lot of work into both improving their APIs and doing so in a cross-compatible way.