这是使用和提供的解决问题的功能解决方案（没有任何 可变变量 ！），该提供者为：
reduce``flatten``underscore.js
function cartesianProductOf() { return _.reduce(arguments, function(a, b) { return _.flatten(_.map(a, function(x) { return _.map(b, function(y) { return x.concat([y]); }); }), true); }, [ [] ]);}// [[1,3,"a"],[1,3,"b"],[1,4,"a"],[1,4,"b"],[2,3,"a"],[2,3,"b"],[2,4,"a"],[2,4,"b"]]console.log(cartesianProductOf([1, 2], [3, 4], ['a']));<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore.js"></script>
