~ tilde shortcut | is it in the array?

gistfile1.js

//~ is a bitwise NOT operator, which will return 0 only for -1.
// check http://stackoverflow.com/questions/18347033/how-to-shorten-my-conditional-statements/18347047#answer-18347047
var test = { type: 3 };

if ( ~[1, 2, 3, 4].indexOf(test.type) ) {
    alert('woohooo!');
}