TypeScript - pad right number in string with zeros or spaces to get determined length

In TypeScript it is possible to pad any number with some character in the following ways:

• with simple custom method (Example 1),
• with padEnd method placed inside String class (Example 2 and 3) - introduced in ES2017 - is not supported in older browsers.

1. Custom solution example

In this section custom solution on how to pad any characters on the right side is presented.

function padRight(number: number, length: number, character?: string): String {
  if (character == null) {
    character = ' ';
  }
  let result = new String(number);
  for (let i = result.length; i < length; ++i) {
    result += character;
  }
  return result;
}

// Usage example:

console.log(padRight(123, 2) + ' ' + padRight(456, 2));
console.log(padRight(123, 4) + ' ' + padRight(456, 4));
console.log(padRight(123, 6, ' ') + ' ' + padRight(456, 6, ' '));
console.log(padRight(123, 6, '*'));
console.log(padRight(123, 6, '.'));
console.log(padRight(123, 6, '0'));

Output:

123 456
123  456 
123    456   
123***
123...
123000

2. Polifill example

ECMAScript 2017 introduced a function that pads numbers.

2.1. Inline code example

In this section presented code uses copied method from the polyfill library. Before using padStart() method, install ts-polyfill package first.

npm install ts-polyfill

Example:

// https://github.com/ryanelian/ts-polyfill
// https://developer.mozilla.org/en-US/docs/Web/TypeScript/Reference/Global_Objects/String/padEnd

import 'ts-polyfill/lib/es2017-string';

const text1 = '123';
const text2 = '456';

console.log(text1.padEnd(2) + ' ' + text2.padEnd(2));
console.log(text1.padEnd(4) + ' ' + text2.padEnd(4));
console.log(text1.padEnd(6, ' ') + ' ' + text2.padEnd(6, ' '));
console.log(text1.padEnd(6, '*'));
console.log(text1.padEnd(6, '.'));
console.log(text1.padEnd(6, '0'));

Output:

123 456
123  456     
123    456   
123***       
123...
123000

See also

1. TypeScript - pad left number in string with zeros or spaces to get determined length