Code Editor (JavaScript)
// Requires an explicit PixelType if no data.
var empty = ee.Array([], ee.PixelType.int8()); // Empty []
var one = ee.Array([1]);
var two = ee.Array([2]);
print(ee.Array.cat([empty])); // []
print(ee.Array.cat([empty, empty])); // []
print(ee.Array.cat([empty, one])); // [1]
print(ee.Array.cat([one, empty])); // [1]
print(ee.Array.cat([one, two])); // [1, 2]
print(ee.Array.cat([one, two], 0)); // [1, 2]
print(ee.Array.cat([one, two], 1)); // [[1,2]]
var a = ee.Array([0, 1, 2]);
var b = ee.Array([3, 4, 5]);
print(ee.Array.cat([a, b])); // [0,1,2,3,4,5]
print(ee.Array.cat([a, b], 0)); // [0,1,2,3,4,5]
print(ee.Array.cat([a, b], 1)); // [[0,3],[1,4],[2,5]]
var c = ee.Array([[0], [1], [2]]);
var d = ee.Array([[3], [4], [5]]);
print(ee.Array.cat([c, d])); // [[0],[1],[2],[3],[4],[5]]
print(ee.Array.cat([c, d], 0)); // [[0],[1],[2],[3],[4],[5]]
print(ee.Array.cat([c, d], 1)); // [[0,3],[1,4],[2,5]]
print(ee.Array.cat([c, d], 2)); // [[[0,3]],[[1,4]],[[2,5]]]
var e = ee.Array([[[0, 1], [2, 3]], [[4, 5], [6, 7]]]);
var f = ee.Array([[[10, 11], [12, 13]], [[14, 15], [16, 17]]]);
// [[[0,1],[2,3]]
// [[4,5],[6,7]]
// [[10,11],[12,13]]
// [[14,15],[16,17]]
print(ee.Array.cat([e, f], 0));
// [[[0,1],[2,3],[10,11],[12,13]]
// [[4,5],[6,7],[14,15],[16,17]]]
print(ee.Array.cat([e, f], 1));
// [[[0,1,10,11],[2,3,12,13]]
// [[4,5,14,15],[6,7,16,17]]]
print(ee.Array.cat([e, f], 2));
// [[[[0,10],[1,11]],[[2,12],[3,13]]]
// [[[4,14],[5,15]],[[6,16],[7,17]]]]
print(ee.Array.cat([e, f], 3));