[Javascript - convert and append] - using a textarea and button, convert underscore_case to camelCase, pad and append

script.js

document.body.append(document.createElement('textarea'));
document.body.append(document.createElement('button'));

document.querySelector('button').addEventListener('click', function () {
    const text = document.querySelector('textarea').value;
    const rows = text.split('\n');

    for (const [i, row] of rows.entries()) {
        const [first, second] = row.toLowerCase().trim().split('_');
        const output = `${first}${second.replace(second[0], second[0].toUpperCase())}`;
        console.log(`${output.padEnd(20)}${'✅'.repeat(i + 1)}`);
    }
});

/* Test Data
underscore_case
 first_name
Some_Variable
 calculate_AGE
delayed_departure
*/