JavaScript numbers to Words

Question

I\'m trying to convert numbers into english words, for example 1234 would become: \"one thousand two hundred thirty four\".

My Tact

Answer 1

I am providing here my solution for converting numbers to the equivalent English words using the Single Loop String Triplets (SLST) Method which I have published and explained in detail here at Code Review with illustration graphics.

Simple Number to Words using a Single Loop String Triplets in JavaScript

The concept is simple and easily coded and is also very efficient and fast. The code is very short compared with other alternative methods described in this article.

The concept also permits the conversion of very vary large numbers as it does not rely on using the numeric/math function of the language and therefore avoids any limitations.

The Scale Array may be increased by adding more scale names if required after "Decillion".

A sample test function is provided below to generate numbers from 1 to 1099 as an example.

A full fancy version is available that caters for adding the word "and" and commas between the scales and numbers to align with the UK and US ways of spelling the numbers.

Hope this is useful.

/************************************************************/
function NumToWordsInt(NumIn) {
/************************************************************
* Convert Integer Numbers to English Words
* Using the Single Loop String Triplets Method
* @Param : {Number}  The number to be converted
*                    For large numbers use a string
* @Return: {String}  Wordified Number (Number in English Words)
* @Author: Mohsen Alyafei 10 July 2019
* @Notes : Call separately for whole and for fractional parts.
*          Scale Array may be increased by adding more scale
*          names if required after Decillion.
/************************************************************/
  
 if (NumIn==0) return "Zero";
 var  Ones  = ["", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen"],
      Tens  = ["", "", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety"],
      Scale = ["", "Thousand", "Million", "Billion", "Trillion", "Quadrillion", "Quintillion", "Sextillion", "Septillion", "Octillion", "Nonillion", "Decillion"],
      N1, N2, Sep, j, i, h, Trplt, tns="", NumAll = "";
 NumIn += "";                                            // Make NumIn a String
//----------------- code starts -------------------
 NumIn = "0".repeat(NumIn.length * 2 % 3) + NumIn;       //Create shortest string triplets 0 padded
 j = 0;                                                  //Start with the highest triplet from LH
    for (i = NumIn.length / 3 - 1; i >= 0; i--) {        //Loop thru number of triplets from LH most
      Trplt = NumIn.substring(j, j + 3);                 //Get a triplet number starting from LH
      if (Trplt !="000") {                               //Skip empty trplets
        Sep = Trplt[2] !="0" ? "-":" ";                  //Dash only for 21 to 99
        N1 = Number(Trplt[0]);                           //Get Hundreds digit
        N2 = Number(Trplt.substr(1));                    //Get 2 lowest digits (00 to 99) 
        tns = N2 > 19 ? Tens[Number(Trplt[1])] + Sep + Ones[Number(Trplt[2])] : Ones[N2];
        NumAll += ((h = N1>0 ? Ones[N1] + " Hundred": "") + " " + tns).trim() + " " + Scale[i]+ " "; 
      }
      j += 3;                                            //Next lower triplets (move to RH)
    }
//----------------- code Ends --------------------
 return NumAll.trim();                                   //Return trimming excess spaces if any
}



// ----------------- test sample -----------------
console.log(NumToWordsInt(67123))
console.log(NumToWordsInt(120003123))
console.log(NumToWordsInt(123999))
console.log(NumToWordsInt(789123))
console.log(NumToWordsInt(100178912))
console.log(NumToWordsInt(777))
console.log(NumToWordsInt(999999999))
console.log(NumToWordsInt(45))