Input field enter integer only in jQuery

$(document).ready(function () {
    //called when key is pressed in textbox
    $("#quantity").keypress(function (e) {
        //if the letter is not digit then display error and don't type anything
        if (e.which != 8 && e.which != 0 && (e.which < 48 || e.which > 57)) {
            //display error message
            $("#errmsg").html("Digits Only").show().fadeOut("slow");
            return false;
        }
    });
});

Number :
<input type="text" name="quantity" id="quantity" /> <span id="errmsg"></span>

Enter Integrr Number only

Enter Integer only in text fileds
onkeyup="if (/\D/g.test(this.value)) this.value = this.value.replace(/\D/g,'')"

Input field enter integer only

Here's an example that limits a form field to contain only numeric input (on the fly, of course!).

<script type="text/javascript">
function numbersonly(e){
var unicode=e.charCode? e.charCode : e.keyCode
if (unicode!=8){ //if the key isn't the backspace key (which we should allow)
if (unicode<48||unicode>57) //if not a number
return false //disable key press
}
}
</script>

<form>
<input type="text" size=18 onkeypress="return numbersonly(event)">
</form>