I have a number, let's say 9. But I need it as the string "09".
I know I can write my own logic. But I am looking for an implicit utility function which can pad the number.
I am using Angular2 with TypeScript. Looking for something like this.
Just similar to Java:
String.format("%010d", Integer.parseInt(mystring)); You can create your own function for this. To format the number you will have to convert it to a string first:
function pad(num, size) { let s = num+""; while (s.length < size) s = "0" + s; return s; } TypeScript:
pad(num:number, size:number): string { let s = num+""; while (s.length < size) s = "0" + s; return s; } Edit: There are a couple of better and more performant ways to do this. See the discussion in this answer (I recommend reading most of the submitted answers if you got time): https://stackoverflow.com/a/9744576/1734678
Update: ECMAScript 2017 now has support for string padding:
str.padStart(targetLength [, padString]) str.padEnd(targetLength [, padString]) Check out padStart's documentation.
EDIT: As mentioned by others, since Angular 4 you can use this:
{{ myNumber | number:'2.0' }} 
Since Angular v4 there is DecimalPipe which let's easily add leading zeros: https://angular.io/api/common/DecimalPipe
In your html, you can use then something like:
{{ myNumber | number:'2.0' }}
You can use one of below templates in HTML
{{ ("00" + 9).slice(-2) }} // 09 Or
{{ 9 | number: '2.' }} // 09 Or in component ts code file
var x = ("00" + 9).slice(-2); 
if i want to pad "0" at the start and want the length of the String str to be 9:
str.padStart(9 ,"0") With the latest Typescript, you can do:
let myStr:string = padLeft('123', '0', 6); // '000123' padLeft(text:string, padChar:string, size:number): string { return (String(padChar).repeat(size) + text).substr( (size * -1), size) ; } 
(String(padChar).repeat(size - text.length) + text)
public padIntegerLeftWithZeros(rawInteger: number, numberOfDigits: number): string { let paddedInteger: string = rawInteger + ''; while (paddedInteger.length < numberOfDigits) { paddedInteger = '0' + paddedInteger; } return paddedInteger; } public zeroPadIntegerLeft3Digits(rawInteger: number): string { return this.padIntegerLeftWithZeros(rawInteger, 3); } You can create a Pipe for that
{{ID |LeftPadFilter: ID}} import { Pipe, PipeTransform } from '@angular/core'; @Pipe({ name: 'LeftPadFilter', pure: false }) export class LeftPadFilter implements PipeTransform { transform(item: string): string { return (String('0').repeat(2) + item).substr((2 * -1), 2); } } 
export function Dx(num: any, dn: number = 2) { return ("0".repeat(dn) + Math.floor(num)).slice(-dn); } 