allowing input only for float number

Question

I have pain-time when making input that only allows float number with jquery library. my code can\'t prevent chacacter \".\" when it\'s becoming first input, can anyone guid

Answer 1

Here is my solution, works with negative numbers too (fiddle)

$("input").keypress(function (event) {
    var inputCode = event.which;
    var currentValue = $(this).val();
    if (inputCode > 0 && (inputCode < 48 || inputCode > 57)) {
        if (inputCode == 46) {
            if (getCursorPosition(this) == 0 && currentValue.charAt(0) == '-') return false;
            if (currentValue.match(/[.]/)) return false;
        } 
        else if (inputCode == 45) {
            if (currentValue.charAt(0) == '-') return false;
            if (getCursorPosition(this) != 0) return false;
        } 
        else if (inputCode == 8) return true;
        else return false;

    } 
    else if (inputCode > 0 && (inputCode >= 48 && inputCode <= 57)) {
        if (currentValue.charAt(0) == '-' && getCursorPosition(this) == 0) return false;
    }
});
function getCursorPosition(element) {
    if (element.selectionStart) return element.selectionStart;
    else if (document.selection)
    {
        element.focus();
        var r = document.selection.createRange();
        if (r == null) return 0;

        var re = element.createTextRange(),
            rc = re.duplicate();
        re.moveToBookmark(r.getBookmark());
        rc.setEndPoint('EndToStart', re);
        return rc.text.length;
    }
    return 0;
}