Existential operator (was: ||= is much needed?)

Brendan Eich brendan at mozilla.org
Mon Jun 18 07:48:12 PDT 2012

Aymeric Vitte wrote:
> Why not, instead of adding "?" operator ? 

You mean ?. here, I assume.

The answer is because what you propose is an incompatible change to 
ECMA-262 (all editions) and JS back to its birth, which lets programs 
that throw currently continue to run, with possibly disastrous 
consequences (undefined flowing into the bank-balance database as NaN). 
There is no way that this kind of potentially-bug-hiding behavior should 
be the default semantics. It must be explicitly opted-into via new syntax.


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