board.js

/* eslint-disable no-lonely-if */
function generateBoard(nbRow, nbCol) {
  const board = []
  for (let i = 0; i < nbRow; i++) {
    const row = []

    for (let j = 0; j < nbCol; j++) {
      if (i % 2 === 0) {
        if (j % 2 === 0) {
          row.push('x')
        } else {
          row.push(' ')
        }
      } else {
        if (j % 2 !== 0) {
          row.push('X')
        } else {
          row.push(' ')
        }
      }
    }

    board.push(row)
  }
  return board
}

function betterGenerate(nbRow, nbCol) {
  let board = new Array(nbRow).fill(new Array(nbCol).fill(''))

  board = board.map((row, i) => {
    return row.map((_, j) => {
      if (i % 2 === 0) {
        return j % 2 === 0 ? 'x' : ' '
      } else {
        return j % 2 === 0 ? ' ' : 'x'
      }
    })
  })

  return board
}

console.log('Easy')
console.table(generateBoard(4, 4))
console.log('---------------------')
console.log('Hard')
console.table(betterGenerate(4, 4))