Code Snippets by Leerlandais

Reg national formatter

Controls the form of an input to only permit numbers and adds symbols where needed

INPUT_NAME.addEventListener("input", function (event) {
    let value = event.target.value.replace(/\D/g, "");    // replace non digits with nothing
    let formatted = "";    // create the empty string
        // As digits are added, count them and take necessary action
        if (value.length > 0) formatted += value.substring(0, 2);
        if (value.length > 2) formatted += "." + value.substring(2, 4);
        if (value.length > 4) formatted += "." + value.substring(4, 6);
        if (value.length > 6) formatted += "-" + value.substring(6, 9);
        if (value.length > 9) formatted += "." + value.substring(9, 11);
    event.target.value = formatted; // change the input to the formatted string
});