Flatten 2D array of numbers into array of objects with “row” index?

Full-on brain fart mode today. Can’t think of a clean way to do this without an ugly loop/recursion.

I need to take a 2D array of numbers:

const layoutMatrix = [
  1,
  [1],
  [0.5, 0.5],
  [0.2, 0.4, 0.4],
];

… and convert this to an array of objects where each entry represents a value from this array where span is the value, and row is the index of each first-level array:

[
  { row: 0, span: 1 },
  { row: 1, span: 1 },
  { row: 2, span: 0.5 },
  { row: 2, span: 0.5 },
  { row: 3, span: 0.2 },
  { row: 3, span: 0.4 },
  { row: 3, span: 0.4 },
]

Prerequisites:

1. The array will only ever be 2 levels deep like this, never more. So no need for full-on recursion, I suppose.
2. The values for each entry can be either a number or an array of numbers.

>Solution :

flatMap the outer array, mapping the inner arrays to row, span pairs…

const layoutMatrix = [
  1,
  [1],
  [0.5, 0.5],
  [0.2, 0.4, 0.4],
];

const objs = layoutMatrix.flatMap((value, row) => {
  if (typeof value === 'number') value = [value];
  return value.map((span) => ({ row, span }));
});

console.log(objs);