Simple type checker, inspired by axis

var q = (function () {
  return 'Array,Boolean,Date,Function,Null,Number,Object,RegExp,String,Undefined'.split(',').reduce( function( checker, type ){
  checker['is' + type] = ( function (identity){
    return function (context) {
      return Object.prototype.toString.call(context).slice(8, -1) === identity;
    };
  })( type );
  return checker;
  }, {});
})();