您猜这就是您要找的吗?

guess this is what you're after?

function cartesian_product(xs, ys) {
    var result = [];
    for(var i = 0; i < xs.length; i++) {
        for (var j = 0; j < ys.length; j++) {
            // transform [ [1, 2], 3 ] => [ 1, 2, 3 ] and append it to result []
            result.push([].concat.apply([], [ xs[i], ys[j] ]));
        }
    }
    return result;
}

function cartesian_power(xs, n) {
    var result = xs;
    for(var i = 1; i < n; i++) {
        result = cartesian_product(result, xs)
    }
    return result;
}

// in your case params are [ 1, 2... 30] and 7
console.log(cartesian_power([1, 2, 3, 4], 2));

输出为:

[ [ 1, 1 ],
  [ 1, 2 ],
  [ 1, 3 ],
  [ 1, 4 ],
  [ 2, 1 ],
  [ 2, 2 ],
  [ 2, 3 ],
  [ 2, 4 ],
  [ 3, 1 ],
  [ 3, 2 ],
  [ 3, 3 ],
  [ 3, 4 ],
  [ 4, 1 ],
  [ 4, 2 ],
  [ 4, 3 ],
  [ 4, 4 ] ]

更新

这将需要更少的内存，因为它不会存储任何内容，只会打印输出.但仍然怀疑它是否实用.

this one will require much less memory, since it will not store anything, it will just print the output. but still doubt it's practical.

function print_combs(arr, n, out) {
    if (n === 0) {
        console.log(out);
    } else {
        for(var i = 0; i < arr.length; i++) {
            print_combs(arr, n-1, out+arr[i]);
        }
    }
}

print_combs([1, 2, 3, 4], 2, "");