Problem

Solution

let n = 10;

const star = "*";

for(let i = 1; i <= n; i++) {
  let result = "";

  let left = result.concat(" ".repeat(n-i));

  let center = result.concat("*", star.repeat(2*(i-1)));
  
  let right = result.concat(" ".repeat(n-i));
  
  console.log(left + center + right);
}