piramid.js

function range(limit) {
  return Array.from(Array(limit)).map((_,i) => i)
}

function piramid(height = 10) {
  return range(height).reduce((ret, i) => {
    let space = ' '.repeat(height - i)
    let slope = '*'.repeat(i)
    return ret + `${space}${slope}*${slope}${space}\n`
  }, '\n')
}

for (let i = 1; i < 10; i++) {
  console.log(piramid(i))
}