JQuery How to restict text box and text area to enter number

Try out following JQuery script , It will allow to enter 14,3 combination to text box. i.e
decimal number with max 14 (without .) and maximum of 3 decimal.234.

input type="text" id="transAmtField"/

$(document).ready(function() {
restrictInt(14,3);
});
var oldAmount;
function restrictInt(num,decimal) {
var amount;
var newNum=0;
$("#transAmtField").bind('keyup', function(e) {
amount = $("#transAmtField").val();
if(isNaN(amount)) {
$("#transAmtField").val(amount.replace(/[^0-9\.]/g,''));
return false;
}
if(amount.lastIndexOf(".") != -1) {
if(amount.length-amount.lastIndexOf(".") > decimal+1 ){
$("#transAmtField").val(oldAmount);
return false;
} else if(amount.length <= num+1) {
oldAmount = amount;
return true;
} else {
oldAmount = amount.substring(0,num+1);
$("#transAmtField").val(oldAmount);
return false;
}
}
if(amount.lastIndexOf(".") == -1) {
if(amount.length <= num) {
return true;
} else {
oldAmount = amount.substring(0,num);
$("#transAmtField").val(oldAmount);
return false;
}
}
});
}