Question

I have a textbox where I’m using jQuery to limit the input to numeric characters only. The issue I’m having is that when the 4 digit code starts with a 0, it gets deleted from the textbox on focusout or when another number is entered. It’s an mvc3 application and the datatype is string. How do I keep the leading zero from being deleted? Is there something I’m not noticing in my jQuery code? This also applies if there are multiple leading zeros for example, “0025”.

$('#selector').bind('keyup paste', function (e) {
if (checkArrowKeyEntry(e)) {
    var ob = $(this);
    if (e.type == 'paste') {
        setTimeout(function () {
            myFuncion(ob);
        }, 1);
    } else {
        myFuncion(ob);
    }
}
});

function myFuncion(ob) {
ob.val(numericInputOnly(ob.val()));
}

function checkArrowKeyEntry(e) {
isNotArrowKey = true;
if (e.keyCode == 37 || e.keyCode == 39) { //|| e.keyCode == 8 || e.keyCode == 46) {
    // leftarrow, rightarrow, delete, backspace
    isNotArrowKey = false;
}
return isNotArrowKey;
}

function numericInputOnly(inputvalue) {
if (!isNaN(parseInt(inputvalue, 10))) {
    inputvalue = parseInt(inputvalue, 10);
}
else {
    inputvalue = "";
}
inputvalue = inputvalue.toString().replace(/[^0-9]/g, '');
return inputvalue;
}

Answer 1

I suspect there is something wrong in the numericInputOnly function.

You correctly make sure that it always outputs a string (so that the leading 0s do not get trimmed out), but you convert the inputValue to a string too early.

the bug in your code is on the line :

inputvalue = parseInt(inputvalue, 10);

converting to an int will “lose” the trailing 0s.

Try for example with

function numericInputOnly(inputvalue) {
    return inputvalue.replace(/[^0-9]/g, '');
}

this will keep only the digits that were typed (all digits including leading 0s) and might correspond to what you need.