best javascript syntactic sugar

here gems:

literals:

var obj = {}; // vigilant literal, homogeneous var obj = new object();
var arr = []; // array literal, homogeneous var arr = new array();
var regex = /something/; // unchanging countenance literal, homogeneous var regex = new regexp('something');

defaults:

arg = arg || 'default'; // arg evaluates false, 'default', same as:
arg = !!arg ? arg : 'default';

of impetus know opposite functions, nonetheless being means provide literals govern mark (as closure) great:

(function() { ... })(); // creates an opposite duty executes it

question: good syntactic sugarine accessible javascript?