July 2nd, 2008
Last week it came out that, in Firefox (and other Gecko-based browsers) you could dip into the private scope of a function using eval, like so:
// Getting "private" variables
var obj =
(function() {
var a =
21;
return {
// public function must reference 'a'
fn:
function() {a;
}
};
})();
var foo;
eval('foo=a', obj.fn);
console.log(foo); // 21
I think the common response to seeing the above was something like: WUH!?!?
As can be seen in the ensuing discussions.
Perhaps more interestingly is the dig in to try and figure out how on earth this feature made it in to the language to being with. Brendan Eich provides some insight:
3.2 <fur> 1998-04-23 17:30: Initial checkin of JavaScript 1.3, migrated from JSFUN13_BRANCH in /m/ src repository
This eval extension, if memory serves (I was in mozilla.org at the time, not in the JS group at Netscape) originated in conversations with Microsoft's rep during ECMA-262 standardization, trying to reach agreement on a way to eval in other scopes.
At this point, however, it's pretty safe to say that since so few people know about it, and that (hopefully) there are no important sites relying upon its behavior, it can be stricken from the record.
Which it has been.
It's been a crazy ride but you can expect to see this feature gone in Firefox 3.1 (the next release of Firefox, set to debut this year).
Tags: firefox, mozilla, javascript, links
19 Comments on 'eval() Kerfuffle'
June 25th, 2008
Visit: New CSS Features in Firefox 3
David Baron, a Mozilla developer, has a write-up on the new CSS features that are available in Firefox 3. There's a mix of additions - everything from CSS 2.0 and 2.1 features to new additions that are tracking CSS 3.
Some of my favorite additions include:
The CSS 3 Box Specification (in the form of -moz-max-content, -moz-min-content, -moz-fit-content, and -moz-available values to width, min-width, and max-width).
-moz-fit-content actually does let authors do some things that previously weren't possible without tables, such as putting a background on headings that doesn't fill the whole width of the container unless the heading does, but is a single rectangle if the heading breaks to multiple lines (see Demo).
Wrapped whitespace (white-space: pre-wrap). This allows you to have a <pre/> whose contents are wrapped nicely, while still maintaining its rigid structure.
rgba() values. You can now apply opacity directly to background colors (as opposed to having to create a shim div/span and styling that instead). Note that the below text is fully opaque.
body { background: url(stripes-6); }
div { background: rgba(0, 255, 0, 0.5); }
h2 { background: rgba(255, 0, 0, 0.5); }
inline-block and inline-table Such a powerful addition - and one that now brings Firefox in line with most other browsers. It'll allow you to create much-more-complicated layouts that were previously very trying to implement using normal CSS. Demo.
Tags: firefox, mozilla, css, links
13 Comments on 'New CSS in Firefox 3'
