Chris Wilson: What I think about ES4

liorean liorean at
Sun Nov 4 10:56:15 PST 2007

On 04/11/2007, Mitch Skinner <lists at> wrote:
> Nicolas Cannasse wrote:
> > Mozilla and Adobe thought the same and came up with the
> > ScreamingMonkey project, which is an ES4 runtime that can be installed
> > for Internet Explorer. Nice, but how long will that work ? Given that
> > Microsoft has no intention of helping, I can foresee that each
> > IE/Windows update will break something.
> I thought that ScreamingMonkey planned on using a published & fairly
> stable API to do this.  Does anyone know of non-Microsoft users of this
> API?  How hard would it be for them to break it?

Very, very hard. The API might not be considered the most well
designed any longer, but there's hooks for it absolutely everywhere.
Most notably, it's used by WSH (the windows scripting host), by IIS
(in ASP), by IE, by outlook, by visual studio etc.

Microsoft has a compatibility nightmare if they decide to change it by
any other means than adding new features.

> Assuming that vbscript and silverlight use this same API, I have to
> think they'd be pretty conservative with it.  Even if it were to change,
> it couldn't be that hard for ScreamingMonkey to keep up.

First of all, Silverlight uses a brand new scripting engine, called
Managed JScript, that runs on the DLR on top of the .NET CLR. Managed
JScript doesn't use the Active Scripting APIs at all, from what I've
read about it.

Second, Microsoft can do absolutely nothing to it except for
additions. There are outside users of these APIs from both sides, e.g.
the ActiveScripting languages such as ActivePerl, ActivePython,
ActiveRuby, HaskellScript use the API from the scripting engine side,
while programs such as the JScript/VBScript external IDEs/debuggers as
well as several in-house applications in major companies use the API
from the host side.
David "liorean" Andersson

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