An Angular 4 pipe to convert a number to an equivalent words representation for Indian Rupees.

number-to-words.pipe.ts

import { Pipe, PipeTransform } from '@angular/core';

@Pipe({
  name: 'numberToWords'
})
export class NumberToWordsPipe implements PipeTransform {

  a = [
    '',
    'one ',
    'two ',
    'three ',
    'four ',
    'five ',
    'six ',
    'seven ',
    'eight ',
    'nine ',
    'ten ',
    'eleven ',
    'twelve ',
    'thirteen ',
    'fourteen ',
    'fifteen ',
    'sixteen ',
    'seventeen ',
    'eighteen ',
    'nineteen '];

  b = [
    '',
    '',
    'twenty',
    'thirty',
    'forty',
    'fifty',
    'sixty',
    'seventy',
    'eighty',
    'ninety'];

  transform(value: any, args?: any): any {
    if (value) {
      let num: any = Number(value);
      if (num) {
        if ((num = num.toString()).length > 9)  { return 'We are not the Iron Bank, you can lower down the stakes :)'; }
        const n = ('000000000' + num).substr(-9).match(/^(\d{2})(\d{2})(\d{2})(\d{1})(\d{2})$/);
        if (!n) {return ''; }
        let str = '';
        str += (Number(n[1]) !== 0) ? (this.a[Number(n[1])] || this.b[n[1][0]] + ' ' + this.a[n[1][1]]) + 'crore ' : '';
        str += (Number(n[2]) !== 0) ? (this.a[Number(n[2])] || this.b[n[2][0]] + ' ' + this.a[n[2][1]]) + 'lakh ' : '';
        str += (Number(n[3]) !== 0) ? (this.a[Number(n[3])] || this.b[n[3][0]] + ' ' + this.a[n[3][1]]) + 'thousand ' : '';
        str += (Number(n[4]) !== 0) ? (this.a[Number(n[4])] || this.b[n[4][0]] + ' ' + this.a[n[4][1]]) + 'hundred ' : '';
        str += (Number(n[5]) !== 0) ? ((str !== '') ? 'and ' : '') +
        (this.a[Number(n[5])] || this.b[n[5][0]] + ' ' +
        this.a[n[5][1]]) + 'rupee' : '';
        return str;
      } else {
        return '';
      }
    } else {
      return '';
    }
  }
}