wtf.js

/*   VT100 terminal reset (<ESC>c) */

console.log('\033c');

/* numbers comparations */

/**/ [2] == 2;
//// true

/**/ [] + [];
//// ''

/**/ [] == [];
//// false

/**/ typeof [];
//// 'object'

/**/ [] == ![];
//// true

/**/ +[] == +![];
//// true

/* null comparation */

/**/ 0 > null;
//// false

/**/ 0 >= null;
//// true

/**/ 0 == null;
//// false

/**/ 0 <= null;
//// true

/**/ 0 < null;
//// false

/**/ typeof null;
//// 'object'

/**/ null instanceof Object;
//// false

/* math */

/**/ 999999999999999;
//// 999999999999999

/**/ 9999999999999999;
//// 10000000000000000

/**/ -9999999999999999;
//// -10000000000000000

/**/ 0.1 + 0.2 == 0.3;
//// false

/**/ 0.1 + 0.2;
//// 0.30000000000000004

/**/ 3 > 2 > 1;
//// false

/**/ 3 > 2 >= 1;
//// true

/**/ 1/0;
//// Infinity

/**/ typeof Infinity;
//// 'number'

/**/ 1/0;
//// Infinity

/**/ 1/-0;
//// -Infinity

/**/ Infinity == -Infinity;
//// false

/**/ Number.MAX_VALUE;
//// 1.7976931348623157e+308

/**/ Number.MIN_VALUE < 0;
//// false

/**/ Number.MIN_VALUE;
//// 5e-324>

/**/ Math.max() > Math.min();
//// false

/**/ Math.max();
//// -Infinity

/**/ Math.min();
//// Infinity

/* string */

/**/ 'wtf' instanceof String;
//// false

/**/ String('wtf') === new String('wtf');
//// false

/**/ new String('wtf');
/*   { '0': 'w',
       '1': 't',
       '2': 'f' } */

/**/ new String('wtf').toString();
//// 'wtf'

/* NaN */

/**/ typeof NaN;
//// 'number'

/**/ NaN == NaN;
//// false

/* construct function */

/**/ new 0xff.constructor.constructor('console.error("WTF")')();
//// WTF

/**/ new Function('console.error("WTF")')();
//// WTF

/* typeof/instanceof */

/**/ Array instanceof Array;
//// false

/**/ new Array instanceof Array;
//// true

/**/ Math instanceof Math;
/*   TypeError: Expecting a function in instanceof check, but got #<Object>
       at repl:1:18
       at REPLServer.self.eval (repl.js:110:21)
       at Interface.<anonymous> (repl.js:239:12)
       at Interface.emit (events.js:95:17)
       at Interface._onLine (readline.js:203:10)
       at Interface._line (readline.js:532:8)
       at Interface._ttyWrite (readline.js:761:14)
       at ReadStream.onkeypress (readline.js:100:10)
       at ReadStream.emit (events.js:98:17)
       at emitKey (readline.js:1096:12) */

/* finally */

/**/ let count = 0;
/**/ function foo() {
/**/        try { return 999; }
/**/        finally { return ++count; } }
/**/ console.log(foo(), count);
//// 1 1

/* new line */

/**/ function sum(a, b) {
/**/        return
/**/               a + b; }
/**/ console.log(sum(1, 3));
//// undefined