|
|
 | | Crunching, the inner workings | |
ESC heavily relies on complex regular expressions and uses a patternscheme that
is only supported by JScript 5.5+'s regular expression engine. The compression-ratio is
defined in levels whereas level 2 also performs actions taken at level 0 & 1.
Running ESC at level 3 steps through 0,1,2 additionally, und so weiter...
| | | |
Levels 1 thru 3 involves the common method of removing whitespace to decrease the
total size of the files. In the eyes of a programmer this action will render a script
completely unmanageable in the matter of readability and debugging, but to the
script-interpreter a crunched script is just as fine as any other, infact in a theorethical
sense I would go as far as saying scripts processed with ESC are executed faster by an interpreter
since there are less characters in total for it to parse. Not really measureable, but still... :) | | | |
At Level 4 or by using the -$ option additionally instructs ESC to perform global variable
substitution upon the guts of your scripts. Now, some would say this sounds more of an act of
obfuscation. Well, that is correct in a sense, but not the intent. The degree of
obfuscation achieved is merely a bi-product of this technique. The sole and major
concern here is to shorten variable, member and method-names in order to shrink the
total size of your script beyond what's possible with whitespace removal technique used by
the preceeding levels.
Be aware though that processing a script at this level will result in a lossy output,
or atleast semi-lossy since it is practically impossible to restore a script crunched at this level
to its original state again. Atleast, this will require a tremendous work hardly worth
the trouble, so make sure always to KEEP your originals at a safe location.
To my knowledge, ESC is the only tool around being able to perform variable substitution
globally and locally with preserved scopes and still produce interpretable output...
| | | |
What level to choose is up to you, but I suggest your start at the default level (2)
and proceed from there. There are implications involved when crunching at 3 & 4
that you should be aware of before attempting to have a go at them.
Read the the section "Crunching, level by level"
to get the hang of what's being
performed at each level.
| | | | |
|
Copyright(c) 2001-2005 Saltstorm.
All rights reserved.