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[ymik]

Javasсript truth table:

''        ==   '0'           //false
0         ==   ''            //true
0         ==   '0'           //true
false     ==   'false'       //false
false     ==   '0'           //true
false     ==   undefined     //false
false     ==   null          //false
null      ==   undefined     //true
" \t\r\n" ==   0             //true

© and so one