copy, appendTo and appendToCopy for js arrays

arraycopyutil.js

var cpy = function(a){return Array.prototype.slice.call(a)}
,appendTo = function(b,a){var c = cpy(b);c.unshift(a.length,0);a.splice.apply(a,c);return a}
,appendToCopy = function(b,a){return appendTo(b,cpy(a))}

module.exports = {copy:cpy,appendTo:appendTo,appendToCopy:appendToCopy};