jquery for number validation

jquery for number validation

$(document).ready(function () {

             SetNumber();
});

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function SetNumber() {
    $(".NumbersOnly").keydown(function (e) {
        var keyPressed;
        if (!e) var e = window.event;
        if (e.keyCode) keyPressed = e.keyCode;
        else if (e.which) keyPressed = e.which;
        var hasDecimalPoint = (($(this).val().split('.').length - 1) == 0);

        if (keyPressed == 46 || keyPressed == 8 || ((keyPressed == 190 || keyPressed == 110) && (!hasDecimalPoint)) || keyPressed == 9 || keyPressed == 27 || keyPressed == 13 ||
            // Allow: Ctrl+A
            (keyPressed == 65 && e.ctrlKey === true) ||
            // Allow: home, end, left, right
            (keyPressed >= 35 && keyPressed <= 39)) {
            // let it happen, don't do anything
            return;
        }
        else {
            // Ensure that it is a number and stop the keypress
            if (e.shiftKey || (keyPressed < 48 || keyPressed > 57) && (keyPressed < 96 || keyPressed > 105)) {
                e.preventDefault();
            }        }
    });}

<input type="textbox" id="txtage" class='NumbersOnly' />