JSFuck – esoteric JavaScript
jsfuck.com
JSFuck – esoteric JavaScript
1–10 of 39 posts
Re: JSFuck – esoteric JavaScript
#2with eval checked,
alert(1) alert(1);Re: JSFuck – esoteric JavaScript
#3Great abuse of the implicit type conversion system.
Amazing that a simple alert("Hello world!") expands to over 16KB.
Re: JSFuck – esoteric JavaScript
#4with eval checked, alert(1) will produce 1227 chars while alert(1); will produce 9535 chars. Interesting.
Well ; produces 8307 chars on its own (without eval checked) -- which seems kind of inefficient (for such a common character in idiomatic javascript). Looking that their encoder, ';' actually has a specific encoding (which itself has to be encoded) so it looks like there's some inefficient expansion taking place (e.g. '.' has a specified encoding that does not require recursive encoding). Encoding the string "link" in the expansion of ';' appears to be very expensive -- alert is cheap in comparison because you can obtain its letters from Javascript return values (e.g. "l" is pulled out of "false" which is obtained by (![]+"")[2])
I'd imagine that if you were serious about this, you'd implement, say, e=String.fromCharCode (12k chars) and use that to dig yourself out of a lot of this expensive stuff if you need more than one hard-to-encode character.
Re: JSFuck – esoteric JavaScript
#5Great abuse of the implicit type conversion system. Amazing that a simple alert("Hello world!") expands to over 16KB.
Yeah, it wasn't the greatest idea to copy and paste the minified version of jQuery in there...
Re: JSFuck – esoteric JavaScript
#6Amazing! I wonder if it's difficult to "disassemble" the JSFuck code?
Re: JSFuck – esoteric JavaScript
#7Amazing! I wonder if it's difficult to "disassemble" the JSFuck code?
This article is pretty good on piecing it stuff like this together: https://blog.korelogic.com/blog/2015/01/12/javascript_deobfu...
Re: JSFuck – esoteric JavaScript
#8hah. I tried to, eh, encrypt the source code of JSFuck itself at https://raw.githubusercontent.com/aemkei/jsfuck/master/jsfuc...
Re: JSFuck – esoteric JavaScript
#9For those wondering how you get numbers, strings and other primitives from a whole bunch of empty arrays and objects in JavaScript, here's what happens when you do arithmetic and other operations on arrays and objects:
> [] + []
"" (An empty string)
> {} + []
0 (The number zero)
> [] + {}
"[object Object]" (.toString() called on a plain object).
> ![]
false (!{} is the same)
> !![]
true (not false)
> +[]
0 (the number zero)
> -[]
-0 (negative zero)
> +{}
NaN (Not a number, same goes for -{})
> "" + []
"" (empty string)
> "" - []
0 (number zero, not empty string)
And the one that gets more people than the previous list:
> typeof [] === typeof {}
true
Incidentally, some of these things can be useful. For example, +(x) will always evaluate to a double (unless it is preceded by a string), while (x|0) will always evaluate to a 32bit integer. asm.js abuses (to an extent) this to have more control over types, and most JavaScript engines would now store the result of (x|0) as an integer internally instead of a double.
Re: JSFuck – esoteric JavaScript
#10I know this will most likely come as a surprise to most Javascript programmers but all code is represented using only two "characters" deep inside your little computers!