demo/js/vendor/ractive.js
function getStarMap( num ) {
			var ones = '',
				max, binary, starMap, mapper, i;
			if ( !starMaps[ num ] ) {
				starMap = [];
				while ( ones.length < num ) {
					ones += 1;
				}
				max = parseInt( ones, 2 );
				mapper = function( digit ) {
					return digit === '1';
				};
				for ( i = 0; i <= max; i += 1 ) {
					binary = i.toString( 2 );
					while ( binary.length < num ) {
						binary = '0' + binary;
					}
					starMap[ i ] = Array.prototype.map.call( binary, mapper );
				}
				starMaps[ num ] = starMap;
			}
			return starMaps[ num ];
		}
function getStarMap( num ) {
			var ones = '',
				max, binary, starMap, mapper, i;
			if ( !starMaps[ num ] ) {
				starMap = [];
				while ( ones.length < num ) {
					ones += 1;
				}
				max = parseInt( ones, 2 );
				mapper = function( digit ) {
					return digit === '1';
				};
				for ( i = 0; i <= max; i += 1 ) {
					binary = i.toString( 2 );
					while ( binary.length < num ) {
						binary = '0' + binary;
					}
					starMap[ i ] = Array.prototype.map.call( binary, mapper );
				}
				starMaps[ num ] = starMap;
			}
			return starMaps[ num ];
		}
This function returns all the possible true/false combinations for a given number - e.g. for two, the possible combinations are [ true, true ], [ true, false ], [ false, true ], [ false, false ]. It does so by getting all the binary values between 0 and e.g. 11