Type coercion and other of JavaScript's dirty tricks.

dirty-tricks.js

// Date -> Number:
var d = +(new Date());
    // 1281743590756
typeof d;
    // number
 
// almost anything -> String
d += '';
    // '1281743590756'
typeof d;
    // string

// inspired @jdalton - https://twitter.com/#!/jdalton/status/90587625869680640
[value] == 'value';
    // true
    // take advantage of Array's valueOf (i.e., toString)
 
// anything -> Boolean
d = !!d;
    // true
typeof d;
    // boolean

@see http://blog.founddrama.net/2010/08/some-of-javascripts-dirty-tricks/