[ianb]

Eval sure, but the way that type coercion works in Javascript is an error. Boxing in Javascript is an error. You can figure them out, you can code around them, but they are bad and can't be justified. All coercion isn't bad, but some is.

Have you seen code that uses .valueOf() for anything good or useful? new String()?

[BrendanEich]

Pre-JIT-compiling JS VM days, I did see new String used intentionally to eliminate auto-boxing overhead on every method called on a big string.

For ES4 (after AS3), we tried eliminating boxing. This is overtly incompatible, a web-breaking change. It won't fly.

Java has primitives that can be autoboxed or explicitly boxed too, which is why JS has them. I was future-proofing for "LiveConnect", which shipped in Netscape 3 (Nick Thompson did the integration).

But I was also in a terrible ten day hurry, so found unboxed primitives easier to deal with in the Mocha first implementation.

If I did not have the "make it look like Java" and ten-day marching orders, I like to think I would have resisted the lazy-programmer second reason. But it's all water way under the bridge now.

Implicit coercions, e.g., '' => 0, were influence by Perl 4. Nuff said!