shoestring.merge.js

(function( undefined ){
  shoestring.merge = function( first, second ){
		var l = second.length,
			i = first.length,
			j = 0;

		if ( typeof l === "number" ) {
			for ( ; j < l; j++ ) {
				first[ i++ ] = second[ j ];
			}
		} else {
			while ( second[j] !== undefined ) {
				first[ i++ ] = second[ j++ ];
			}
		}

		first.length = i;

		return shoestring( first );
	};
}());