padStart < String < JavaScript

The padStart() of a String pads the string with another string (repeated, if needed) until the resulting string reaches the given length. The padding is applied from the start of the string.

    
    const amount = '5';

    const amountPadStart = amount.padStart(2, '0');

    console.log(amountPadStart);
    // "05"


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

    console.log(maskedNumber);
    // "************5581"