If an element in an NxM matrix is zero, then every element in that row and column should be zero

zeroOutMatrix.ts

// If an element in an NxM matrix is zero, then every element in that row and column should be zero
function zeroOutMatrix(m: number[][]): number[][] {
  const zeroedRows = new Map()
  const zeroedCols = new Map()

  for (let r = 0; r < m.length; ++r) {
    for (let c = 0; c < m[r].length; c++){
      if (m[r][c] === 0) {
        zeroedCols.set(c, true)
        zeroedRows.set(r, true)
      }
    }
  }

  for (let r = 0; r < m.length; ++r) {
    if (zeroedRows.get(r) === true) {
      m[r] = m[r].map(v => 0)
    }
  }

  for (let c = 0; c < m[0].length; ++c) {
    if (zeroedRows.get(c) === true) {
      for (let r = 0; r < m.length; ++r) {
        m[r][c] = 0
      }
    }
  }
  return m
}