//also use arr.reverse function processData(input) { for (let i = 0; i < input; i++) { for (let j = input-1; j > i ; j--) { process.stdout.write(" "); } for (let j = 0; j <= i; j++) { process.stdout.write("#"); } process.stdout.write("\n"); } } process.stdin.resume(); process.stdin.setEncoding("ascii"); _input = ""; process.stdin.on("data", function (input) { _input += input; }); process.stdin.on("end", function () { processData(_input); });