The JavaScript character wall

Mike Samuel mikesamuel at
Mon Dec 18 22:13:20 UTC 2017

On Thu, Dec 14, 2017 at 5:39 AM, Gareth Heyes <gareth.heyes at>

> Hi all
> So many years ago on the sla.ckers forums Yosuke Hasegawa posted
> non-alphanumeric JavaScript. We then worked together to find out the
> smallest possible charset required to execute non-alphanumeric JavaScript.
> We all broke the wall multiple times and Mario Heiderich found the
> character limit was 6 characters. It could not be broken.....

Background for other es-discussers,
links to Yosuke Hasegawa's various obfuscator demos, and IIRC,
Mario's argument about the limit is in "Web Application Obfuscation."

Gareth, is there a working 6 character contender?
That ycombinator thread notes that was broken
when the spec
changed the semantics of [] so that it no longer returns the
global object.

> Enter the pipeline operator and Masato Kinugawa. He found using the
> specified pipeline operator he could break the wall :O. Check it out it is
> awesome:

Looks like somebody has already put together a demo page for it:

> I really hope the pipeline operator gets specified and implemented by the
> various browsers because breaking the wall is a fantastic achievement and
> it's useful too.
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