Number to words

numbertowords.js

function numberToWords(num) {
    if (num === 0) return "zero";

    const underTwenty = ["", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten",
                         "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", 
                         "seventeen", "eighteen", "nineteen"];
    const tens = ["", "", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety"];
    const scales = ["", "thousand", "million", "billion", "trillion", "quadrillion"]; // Extend as needed

    const toWords = (n) => {
        if (n < 20) return underTwenty[n];
        if (n < 100) return tens[Math.floor(n / 10)] + (n % 10 ? " " + underTwenty[n % 10] : "");
        if (n < 1000) return underTwenty[Math.floor(n / 100)] + " hundred" + (n % 100 ? " " + toWords(n % 100) : "");
    };

    if (typeof num !== "number") num = Number(num);
    if (isNaN(num)) return "Not a number";
    let index = 0;
    const parts = [];

    while (num > 0) {
        const part = num % 1000;
        if (part > 0) {
            parts.unshift(toWords(part) + (scales[index] ? " " + scales[index] : ""));
        }
        num = Math.floor(num / 1000);
        index++;
    }

    return parts.join(" ").trim();
}

console.log(numberToWords(12345678901234)); // Example usage