Subj : Re: Slow string conversion of long js functions
To   : netscape.public.mozilla.jseng
From : Adrian Klein <master@dragosan.net>
Date : Mon Jan 12 2004 08:16 pm

Adrian Klein wrote:
> Hi all,
> 
> I occassionally found out that the conversion of javascript functions to 
> their String value in general seems to be very slow and not to scale to 
> well with the length of the function. I was just wondering if this could 
> be a useful hint for a future optimization and where it should be posted 
> if it should at all.
> 
> A Testsite, that performs the conversion of a relative long js function 
> to its String value 10 times (took about 3500 ms on a PII 450 with Win98 
> and Mozilla 1.5, whereas IE and Opera took only about 0 ms): 
> http://www.dragosan.net/slow_string.html
> 

Well the answer I got why String(function) is so slow, is that the 
Spidermonkey Engine needs decompiles script bytecodes back to a String 
representing the function, whereas some other browsers seem to get keep 
the String representation in cache.

What I had was a a skript used in a website that made use of a function 
that created a kind of a reference to another function. My first 
solution to do this was to get the name of the function and the named 
parameters out of the sourcecode of b() via some regular expressions. 
With a function consisting of 2000+ lines of code just the call 
String(function) took 3 seconds to decompile the function.

I could get around this, by supplying the functions name to the function 
that created the references and using the apply function to call the 
referenced function with the arguments passed to a function meant to be 
referencing it.

.