script.js

const character = '!';
const count = 10;
const rows = [];
let inverted = false;
function padRow(rowNumber, rowCount) {
 return (
 ' '.repeat(rowCount - rowNumber) +
 character.repeat(2 * rowNumber - 1) +
 ' '.repeat(rowCount - rowNumber)
 );
}

for (let i = 1; i <= count; i++) {
 if (inverted) {
 rows.unshift(padRow(i, count));
 } else {
 rows.push(padRow(i, count));
 }
}

let result = '';

for (const row of rows) {
 result = result + row + '\n';
}

console.log(result);