Optimize wrapper

[hazzik]

Optimize wrapper based on https://github.com/aemkei/jsfuck/pull/107#issuecomment-684646669.

Replace \ in escape character with t (cheapest symbol outside of base 16 numbers) on compile stage. On runtime stage replace t back with \ before passing the string into the Function constructor. To avoid using replace(x,y) function which requires 2 arguments use split() and join() functions.

The "cost" of additional characters is about ~100.

Without this optimization one unmapped caracter has encoded length of about 3600 characters. Every additional unmapped character adds 2000 to the total length.

For example, the length of ~ is 3605, ~~ is 5600, and ~~~ is 7595.

The loader with replace has encoded length of about 5300 characters and every additional character adds 100 to the total length.

In the same example the length of ~~ becomes 5371 and ~~~ -- 5463.

So, when we have more than one unmapped character we want to encode whole input except select characters (that have encoded length less than about 70) into an escape sequence.

[hazzik]

Btw, the length of JSFuck-encoded jsfuck.js is reduced from 4,711,510 characters to 487,754 characters (10 times!)

[aemkei]

Well, this is a great improvement! Many thanks for taking the time @hazzik !

[aemkei]

Also deployed this version to jsfuck.com.

[hazzik]

Thanks!

[kamil-kielczewski]

@hazzik I was curious how big code of jsfuck.js create small-jsfuck and it creates 258kb of code - Im surprised that pure jsfuck only ~double this result after your fix-es (!). However it looks like they are not deploye yet