3 ms·

why he needed $=[$=[]] and not just $=[[]]

by gcb 16y ago

tlrobinson 16y ago
The second $ (which is actually the first assignment) was used as as an alias to [] before the first $ gets assigned. I guess to reduce the number of characters.
- gcb 16y ago
  it actually increases the number of chars. inner $=[] will be overwritten by outer $=[$], which is the same as $=[[]] or am i missing something?
  - tlrobinson 16y ago
    It doesn't get overwritten until the rest of the expression has been evaluated, thus $ == [] for all the uses of $ within the expression.
    - gcb 16y ago
      still not clear. the code unobfuscated is: (a=[a=[]]['sort'])()['alert'](1) my argument is that this is the same, and less chars (a=[]['sort'])()['alert'](1) I can't see any benefit of the encapsulation of the array assignment there. edit: also, just noticed that my previous comments i was writting $=[[]] when i was thinking of $=[], but both works the same, and are still less chars :)
      - gcb 16y ago
        ($=[][(__=!$+$)[_=-~-~-~$]+({}+$)[_/_]+ ($$=($_=!''+$)[_/_]+$_[+[]])])()[__[_/_]+__ [_+~$]+$_[_]+$$](_/_) on the last string trick to write 'sort' it fails if there's no $=[$=[]] all the other parts just $=[] works just fine. and they are in the same scope as the 't' i can't understand
      - tlrobinson 16y ago
        Ok here's the best I can do: (lines are numbered in order of execution, with explanations of each line) ($=[ // 14: $ = Array.prototype.sort ([]["sort"] = Array.prototype.sort) $=[] // 1: $ = [] ][ (__= !$+$ )[ // 2: __= "false" (![]+[] = false+[] = "false") _=-~-~-~$ // 3: _= 3 (-~-~-~[] = -~-~-(-1) = -~-~(1) = -~-(-2) = -~(2) = -(-3) = 3) ]+ // 4: "s" ("false[3]" = "s") ({}+$)[ // 5: "[object Object]" ({}+[] = "[object Object]") _/_ // 6: 1 (3/3 = 1) ]+ // 7: "o" ("[object Object]"[1] = "o") ($$= // 12: $$ = "rt" ($_= // 9: $_ = "true" !''+$ // 8: "true" (!''+[] = true+[] = "true") )[_/_]+ // 10: "r" ("true"[3/3] = "true"[1] = "r") $_[+$] // 11: "t" ("true"[+[]] = "true"[0] = "t") ) // 13: "rt" ])()[ // 15: window (sort() = window) __[_/_]+ // 16: "a" ("false"[3/3] = "false[1]" = "a") __[_+~$]+ // 17: "l" ("false"[3+(~$)] = "false"[3+(-1)] = "false"[2] = "l") $_[_]+ // 18: "e" ("true"[3] = "e") $$ // 19: "rt" ](_/_) // 20: alert(1) (window["alert"](3/3) = alert(1)) [] is assigned to "$" in step one. Several of the steps between 2 and 11 reference "$" to save one character rather than typing If you wanted to remove the a=[] you'd have to include a bunch of "[]"s inline, e.x.: ($=[][ (__= ![]+[] )[ _=-~-~-~[] ]+ ({}+[])[ _/_ ]+ ($$= ($_= !''+[] )[_/_]+ $_[+[]] ) ])()[ __[_/_]+ __[_+~$]+ $_[_]+ $$ ](_/_) Replacing the no-alpha variable names with letters might help: (F=[ A=[] ][ (B= !A+A )[ C=-~-~-~A ]+ ({}+A)[ C/C ]+ (D= (E= !''+A )[C/C]+ E[+A] ) ])()[ B[C/C]+ B[C+~F]+ E[C]+ D ](C/C) Notice both "A" and "F" were "$". The original code reused "$" to save a character. I'm not sure I can make it any clearer.
        gcb 16y ago
        wow that was sure detailed. but i'm still not convinced of the steps :) ($=[][(__=!$+$)[_=-~-~-~$]+({}+$)[_/_]+ ($$=($_=!''+$)[_/_]+$_[+[]])])()[__[_/_]+__ [_+~$]+$_[_]+$$](_/_) here i kept $, only step 11 required [] instead of $ i'm guessing step 14 is actually executed earlier... or that undefined has the same effects as [] for most of those stringfying hacks. Update: no, undefined trhows an error. so step 14 is earlier... let me replace all that with a eval function that also stores the run order. then i will post the correct ordering.

why he needed $=[$=[]] and not just $=[[]]

by gcb 16y ago

why he needed $=[$=[]] and not just $=[[]]

The second $ (which is actually the first assignment) was used as as an alias to [] before the first $ gets assigned. I guess to reduce the number of characters.

gcb 16y ago
it actually increases the number of chars. inner $=[] will be overwritten by outer $=[$], which is the same as $=[[]] or am i missing something?
- tlrobinson 16y ago
  It doesn't get overwritten until the rest of the expression has been evaluated, thus $ == [] for all the uses of $ within the expression.
  - gcb 16y ago
    still not clear. the code unobfuscated is: (a=[a=[]]['sort'])()['alert'](1) my argument is that this is the same, and less chars (a=[]['sort'])()['alert'](1) I can't see any benefit of the encapsulation of the array assignment there. edit: also, just noticed that my previous comments i was writting $=[[]] when i was thinking of $=[], but both works the same, and are still less chars :)
    - gcb 16y ago
      ($=[][(__=!$+$)[_=-~-~-~$]+({}+$)[_/_]+ ($$=($_=!''+$)[_/_]+$_[+[]])])()[__[_/_]+__ [_+~$]+$_[_]+$$](_/_) on the last string trick to write 'sort' it fails if there's no $=[$=[]] all the other parts just $=[] works just fine. and they are in the same scope as the 't' i can't understand
    - tlrobinson 16y ago
      Ok here's the best I can do: (lines are numbered in order of execution, with explanations of each line) ($=[ // 14: $ = Array.prototype.sort ([]["sort"] = Array.prototype.sort) $=[] // 1: $ = [] ][ (__= !$+$ )[ // 2: __= "false" (![]+[] = false+[] = "false") _=-~-~-~$ // 3: _= 3 (-~-~-~[] = -~-~-(-1) = -~-~(1) = -~-(-2) = -~(2) = -(-3) = 3) ]+ // 4: "s" ("false[3]" = "s") ({}+$)[ // 5: "[object Object]" ({}+[] = "[object Object]") _/_ // 6: 1 (3/3 = 1) ]+ // 7: "o" ("[object Object]"[1] = "o") ($$= // 12: $$ = "rt" ($_= // 9: $_ = "true" !''+$ // 8: "true" (!''+[] = true+[] = "true") )[_/_]+ // 10: "r" ("true"[3/3] = "true"[1] = "r") $_[+$] // 11: "t" ("true"[+[]] = "true"[0] = "t") ) // 13: "rt" ])()[ // 15: window (sort() = window) __[_/_]+ // 16: "a" ("false"[3/3] = "false[1]" = "a") __[_+~$]+ // 17: "l" ("false"[3+(~$)] = "false"[3+(-1)] = "false"[2] = "l") $_[_]+ // 18: "e" ("true"[3] = "e") $$ // 19: "rt" ](_/_) // 20: alert(1) (window["alert"](3/3) = alert(1)) [] is assigned to "$" in step one. Several of the steps between 2 and 11 reference "$" to save one character rather than typing If you wanted to remove the a=[] you'd have to include a bunch of "[]"s inline, e.x.: ($=[][ (__= ![]+[] )[ _=-~-~-~[] ]+ ({}+[])[ _/_ ]+ ($$= ($_= !''+[] )[_/_]+ $_[+[]] ) ])()[ __[_/_]+ __[_+~$]+ $_[_]+ $$ ](_/_) Replacing the no-alpha variable names with letters might help: (F=[ A=[] ][ (B= !A+A )[ C=-~-~-~A ]+ ({}+A)[ C/C ]+ (D= (E= !''+A )[C/C]+ E[+A] ) ])()[ B[C/C]+ B[C+~F]+ E[C]+ D ](C/C) Notice both "A" and "F" were "$". The original code reused "$" to save a character. I'm not sure I can make it any clearer.
      - gcb 16y ago
        wow that was sure detailed. but i'm still not convinced of the steps :) ($=[][(__=!$+$)[_=-~-~-~$]+({}+$)[_/_]+ ($$=($_=!''+$)[_/_]+$_[+[]])])()[__[_/_]+__ [_+~$]+$_[_]+$$](_/_) here i kept $, only step 11 required [] instead of $ i'm guessing step 14 is actually executed earlier... or that undefined has the same effects as [] for most of those stringfying hacks. Update: no, undefined trhows an error. so step 14 is earlier... let me replace all that with a eval function that also stores the run order. then i will post the correct ordering.