Brief talk on ES5 and Mozilla support for it

Tags: , , , , , , — Jeff @ 12:32

I gave a three-minute not-actually-lightning-talk-but-let’s-call-it-that-anyway on ECMA-262 5th edition, what’s in it, and the state of Mozilla’s support for it at the Mozilla weekly meeting this week. It’s probably old hat if you’ve been following the standard closely, but if you haven’t it gives a short and sweet overview of what’s new; there’s a three-minute video of the actual talk on the meeting page (start at around 7:00 into the complete video). If you’re strapped for time, view the slides and turn off stylesheets (View > Page Style > No Style in Firefox) to see notes on what roughly accompanied each slide.


  1. Hey, what happened to the strongly typed version of JavaScript that was to be called JavaScript 2.0?

    Comment by Harsh — 09.02.10 @ 12:20

  2. If you go to the first slide (after the title page), you’ll see this:

    ECMA-262 3rd edition (ES3, 1998)
    ECMA-262 5th edition (ES5, 2009)

    The version with better typing was ES4, which ended up being scrapped due to complaints about scale (a number of which I thought valid) and due to mundane standards politics. This wasn’t entirely bad — ES4 was, I think, overly ambitious — but it did mean we lost out on some useful opt-in ideas to avoid type errors, and we lost out on having a single syntax for class-based systems (like Base.js and others have been reinventing with different boilerplate for years). (And for anyone out there who says type errors don’t happen, I can point you to at least one I’ve written in JS that had to be painfully debugged; optional but enforced type annotations of the kind ES4 had would have eliminated that problem.)

    Comment by Jeff — 09.02.10 @ 12:33

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