JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" name="num_field" placeholder="Enter number" value="1453" id="num_field" />

JavaScript

jQuery(document).ready(function() {
            $("#num_field").val(digitGroup($("#num_field").val()));
        });

        $(function() {
            $("#num_field").keyup(function() {
                var dInput = $(this).val();
                var output = digitGroup(dInput);
                $(this).val(output);
            });
        });

        function digitGroup(dInput) {
            var output = "";
            try {
                dInput = dInput.replace(/[^0-9]/g, ""); // remove all chars including spaces, except digits.
                var totalSize = dInput.length;
                for (var i = totalSize - 1; i > -1; i--) {
                    output = dInput.charAt(i) + output;
                    var cnt = totalSize - i;
                    if (cnt % 3 === 0 && i !== 0) {
                        output = " " + output; // seperator is " "
                    }
                }
            } catch (err)
            {
                output = dInput; // it won't happen, but it's sweet to catch exceptions.
            }
            return output;
        }