Validate number jquery

Number validation with an append at focus/reset at blur

HTML

<input type="text" min="0" max="1000" step="1" id="distance" />

JavaScript

$(document).ready(function() {
    $("#distance");
    $("#distance").focus(OnFocus);
    $("#distance").blur(OnBlur);
});

function PassNumbersOnly(evt) {
    var theEvent = evt || window.event;
    var key = theEvent.keyCode || theEvent.which;
    key = String.fromCharCode(key);
    var regex = /^([0-9]){2}([a-zA-Z]){5}([0-9]){4}([a-zA-Z]){1}([0-9]){1}([a-zA-Z]){1}([0-9]){1}?$/;
    if (!regex.test(key)) {
        theEvent.returnValue = false;
        if (theEvent.preventDefault) {
            theEvent.preventDefault();
        }
    }
}

function OnFocus() {
    var $this = $(this);
    if ($this.val().indexOf("Miles") != -1) {
        $this.val($this.val().split(" ")[0]);
    }
}

function OnBlur() {
    var $this = $(this);
    if ($.trim($this.val()) != "") {
        $this.val($this.val() + " Miles");
    }
}