keycloak_theme/src/tools/formatNumber.ts

export const formatNumber = (input: string, format: string): string => {
    if (!input) {
        return "";
    }

    // array holding the patterns for the number of expected digits in each part
    const digitPattern = format.match(/{\d+}/g);

    if (!digitPattern) {
        return "";
    }

    // calculate the maximum size of the given pattern based on the sum of the expected digits
    const maxSize = digitPattern.reduce(
        (total, p) => total + parseInt(p.replace("{", "").replace("}", "")),
        0
    );

    // keep only digits
    let rawValue = input.replace(/\D+/g, "");

    // make sure the value is a number
    if (`${parseInt(rawValue)}` !== rawValue) {
        return "";
    }

    // make sure the number of digits does not exceed the maximum size
    if (rawValue.length > maxSize) {
        rawValue = rawValue.substring(0, maxSize);
    }

    // build the regex based based on the expected digits in each part
    const formatter = digitPattern.reduce((result, p) => result + `(\\d${p})`, "^");

    // if the current digits match the pattern we have each group of digits in an array
    let digits = new RegExp(formatter).exec(rawValue);

    // no match, return the raw value without any format
    if (!digits) {
        return input;
    }

    let result = format;

    // finally format the current digits accordingly to the given format
    for (let i = 0; i < digitPattern.length; i++) {
        result = result.replace(digitPattern[i], digits[i + 1]);
    }

    return result;
};