On Jun 27, 2008, at 6:51 AM, Pratap Lakshman (VJ#SDK) wrote: > The side effect is as follows: if “this” does not have a “length” > property, it ends up getting one; if “this” does have a length > property, but is not an Array, that “length” property will get > updated.
True, and not just for pop -- for all generic Array methods that mutate length. > What is the rationale for this? I don't recall a detailed rationale on this point, but the pseudo- code is simplest without a special case that avoids creating a 'length' property if one does not exist, and it's easy to rationalize "caveat hacker" -- if you wrote Array.prototype.pop.call(p), you wanted to have effects on your pizza ;-). The simpler specs are a good thing. Trying to change this now seems dicey. We don't know if any web scripts count on this edge case. Creating length may be a requirement because lazy pizza coders left 'length' out, knowing it would be created, and then depended on it becoming 0 (e.g., in a < expression -- if undefined it would become NaN and the condition would be false). There does not seem to be any profit in taking risk by changing the semantics. /be _______________________________________________ Es4-discuss mailing list Es4-discuss@mozilla.org https://mail.mozilla.org/listinfo/es4-discuss
