javascript padstart

const str1 = '5';

console.log(str1.padStart(2, '0'));
// expected output: "05"

const fullNumber = '2034399002125581';
const last4Digits = fullNumber.slice(-4);
const maskedNumber = last4Digits.padStart(fullNumber.length, '*');

console.log(maskedNumber);
// expected output: "************5581"
str.padStart(targetLength [, padString])export function padStart(number, digits = 2, emptyDigit = 0) {
	let length = 0;
	let n = Math.abs(number);
	let absoluteNumber = n;
	do {
		n /= 10;
		length++;
	} while (n >= 1);
	const prefix = Array(Math.max((digits - length) + 1, 0)).join(emptyDigit);
	return number < 0 ? `-${prefix}${absoluteNumber}` : prefix + number;
}

export default padStart;