Development Mode/Production Mode

Wes Garland wes at
Sun Apr 1 04:38:45 PDT 2012

In a similar vein, I would personally like to have
zero-cost-when-not-debugging assert() statements, and am hopeful that
statically-linked modules might lead the way.

We currently have LOW cost assert() statements, but these are still not
suitable for hot loops. We can turn them into zero-cost with some
pre-processing, but to actually guarantee that the program is the same with
and without the asserts (ignoring side effects of the argument) means that
the pre-processor needs to be much trickier than a simple sed statement.
Especially given ASI.

As a data point, we compile all our code through Mozilla's SpiderMonkey
engine with JSOPTION_STRICT, which pre-dates ES5 strict mode, during our
build phase.  It catches a few things for us that would otherwise cause a
bit of head-scratching, like functions that don't always return value.


On 1 April 2012 04:28, Brandon Benvie <brandon at> wrote:

> Forgive me if this has been discussed before but I read back as much as I
> could and couldn't find a reference. With all the discussion that has
> happened in the past about various modes, ES6 strict opt-in, etc. there
> never seems to be mention of the concept of an optional especially strict
> mode specifically designed for development. The premise is this: when I
> developer something I want as many early errors as possible and nothing
> hidden away behind some abstraction, so it can be fixed. When something
> goes live it just needs to work, or gracefully fail, hopefully landing in
> error handlers that were provided, while sending home debug information.
> All of the discussion I've seen doesn't seen to be from this kind of angle,
> more of all or nothing it seems.
> There isn't some sort of mode toggle under discussions for ES6 that is
> specifically anticipated as a dev/production toggle, is there?
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Wesley W. Garland
Director, Product Development
PageMail, Inc.
+1 613 542 2787 x 102
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