We Keep Coding

How can I modify JavaScript to not allow letters in a field?

I am using isNAN at the moment but I can't seem to get it to work.
if (isNAN(getElementById("Bob")))

You can use something along the lines of this function to basically check if inp has letters in it.
function checkLetter(inp)
{
var letters = /^[A-Za-z]+$/;
if(inp.value.match(letters)){
//Letters
}
else {
//no letter
}
}

Try this:
if (isNaN(document.getElementById("Bob").value))
You are not using proper syntax in your code to get value. Also make sure you are using isNaN() and not isNAN().
If you want to check empty values also:
var myVar = document.getElementById("Bob").value;
if(!myVar || isNaN(myVar))
alert("Not a number!");
else
alert("Is a number!");

you have to check the value, not the object
if (isNAN(getElementById("Bob").val()) ){
//
}
EDIT so if you just want lock the field contains numeric values you can do this in html5 :
<input type="number" />

Here is a way to check if only number exists not letters
function isNumber(n) {
return !isNaN(parseFloat(n)) && isFinite(n);
}
So the use will be like
nn=document.getElementById("Bob").value;
ans=isNumber(nn);
if(ans)
{
//only numbers
}
This ans was found from here
Validate numbers in JavaScript - IsNumeric()

jQuery Validation, Numeric Value Only

I'm trying to validate a form input value. The function below states is the value of the input is a number below 150, show error. Works as it should. However, I want to add to it. If the value contains ANYTHING other than a numeric value AND/OR is a value under 150, show error...
How can I modify?
if ($('.billboard-height').val() < 150) {
$('.sb-billboardalert').fadeIn(600);
}

Since your more thorough validation should be on the server-side anyway, you could just use parseInt or parseFloat depending on what sort of value you are expecting. Then check if the result is actually a number and that it also meets your constraints:
var number = parseFloat($('.billboard-height').val()); // or parseInt depending on expected input
if (isNaN(number) || number < 150) {
$('.sb-billboardalert').fadeIn(600);
}
EDIT:
Based on your comments, you are entering regex land. I gather you only ever want a natural number (and the way parseInt/parseFloat ignores trailing non-numeric characters like px, em, etc. is not ok). How about:
var val = $('.billboard-height').val();
var number = parseInt(val, 10);
if ( ! val.match(/^[0-9]{3,4}$/) || number < 150) {
$('.sb-billboardalert').fadeIn(600);
}
This should only allow natural numbers 150-9999.

I would suggest using regexes:
var intRegex = /^\d+$/;
var floatRegex = /^((\d+(\.\d *)?)|((\d*\.)?\d+))$/;
var str = $('#myTextBox').val();
if(intRegex.test(str) || floatRegex.test(str)) {
alert('I am a number');
...
}
Or with a single regex as per #Platinum Azure's suggestion:
var numberRegex = /^[+-]?\d+(\.\d+)?([eE][+-]?\d+)?$/;
var str = $('#myTextBox').val();
if(numberRegex.test(str)) {
alert('I am a number');
...
}
ref: checking if number entered is a digit in jquery

Don't forget the radix parameter in parseInt():
if (parseInt($('.billboard-height').val(), 10) < 150) {
It's probably faster than using a regex. Regular expressions are not known for being fast, but they are very powerful. It might be overkill for this scenario.

You can try out HTML5's built in form validation:
<input type="number" min="150">
browser support is still pretty shakey though

Any value from an input or select will be a string in javascript. You need to use parseInt() to use operators like > or <. == can be used if you use it to compare to a string like if ($('.billboard-height').val() == "150")

Try parseInt and isNaN functions for check if value is number and less than 150:
var intVal = parseInt($('.billboard-height').val());
if(!isNaN(intVal)){ //not Number
if (parseInt($('.billboard-height').val()) < 150) { //not less than 150
$('.sb-billboardalert').fadeIn(600);
}
}

If you need to support floating point numbers, you can check if a variable is valid using:
function isNumber (n) {
return !isNaN(parseFloat(n)) && isFinite(n);
}
var val = $('.billboard-height').val();
if (isNumber(val) && parseFloat(val) < 150) {
$('.sb-billboardalert').fadeIn(600);
}
If you only need to support integers, use parseInt(n, 10), where 10 is the base to convert the string to.
var val = parseInt($('.billboard-height').val(), 10);
if (val && val < 150) {
$('.sb-billboardalert').fadeIn(600);
}

// Displays an alert if s contains a non-numeric character.
function alertForNonNumeric(s) {
var rgx = /[^0-9]/;
if (s.search(rgx) !== -1) {
alert("Input contains non-numeric characters!");
}
}
JS Fiddle here
NOTE: If you want to check for negative ints as well, you can add a minus sign to the regex:
function alertForNonNumeric(s) {
var rgx = /[^0-9-]/;
if (s.search(rgx) !== -1) {
alert(s + " contains non-numeric characters!");
}
}

I use this solution, I find it quite ellegant - no alerts, user is effectively unable to enter non numeric characters.
This is jQuery example:
function digitsOnly(){
// extract only numbers from input
var num_val = $('#only_numbers').val().match(/\d+/);
$('#only_numbers').val(num_val);
}
Your html:
<input type="text" name="only_numbers" id="only_numbers" on oninput="digitsOnly();"/>

jQuery Form, check first four numbers of variable

What I'm trying to achieve is a code checker. Only the first 4 numbers are important, the other numbers can be any number. The form will be used for users to put in productcodes.
The problem is that if the variable changes to say, 5 numbers the variable is false.
See below example:
http://jsfiddle.net/MZfxs/3/
If the user puts in the numbers 3541 the box changes color, but if the user put in the remaining numbers the value is set to false.
Additionally I'm trying to make the box only change color when 13 numbers are inserted AND the first 4 numbers are matching, in that order.
Solved!
Working Example:
http://jsfiddle.net/MZfxs/8/

If I understood correctly, you need a field value validation and the requirement is the value should start from 4 numbers like 7514 or 9268. Here you can use a regular expression to validate input value like:
// Will work for " 123433 " or "12345634 ", etc.
var value = $(this).val(),
re = /^\s*(\d{4})(\d+)\s*$/, // better to initialize only once somewhere in parent scope
matches = re.exec(value),
expectedCode = 3541,
expectedLength = 13;
if(!!matches) {
var code = matches[1]; // first group is exactly first 4 digits
// in matches[2] you'll find the rest numbers.
if(value.length == expectedLength && code == expectedCode) {
// Change the color...
}
}
Also if your requirement is strict to length of 13 than you can modify the regular epression to
var re = /^(\d{4})(\d{9})$/;
and retrieve first 4 numbers in first group and rest 9 in second group:
var matches = re.exec(value);
if(!!matches) {
var first4Digits = matches[1],
rest9Digits = matches[2];
// ...
// Also in this way you'll not need to check value.length to be 13.
}

You can break the string each time on key event fires. You can do this by calling js substring() method and take the first four characters and check it.

Try to use this:
<script>
$("input").keyup(function () {
var value = $(this).val();
$("p").text(value);
var value2 = $(this).val().substr(0,4);
if(value2 == 3541){
$(".square").css("background-color","#D6D6FF");
}else{
$(".square").css("background-color","yellow");
}
})
</script>

Error with validation process by input data

Goal:
I dont wanna retrieving any data if the input data contain any alphabet.
Problem:
If I have input data "23w" in variable ddd, the process on convertion is accceptable to be "23" in the variable currentvalue.
I don't want it to be converted into number if the input data contain
any alphabet.
The sourcecode is writtin in jQuery and if possible it would be great to retreive the new solution in jQuery.
// Fullmetalboy
var ddd = $('#field_hourInput').val();
var currentValue = parseInt(ddd);
// Validating message
if(currentValue <= 0)
{
alert("Value must be positiv");
nonError = false;
}
else if( (isNaN(currentValue)) && (ddd != "") )
{
alert("value must contain numbers");
nonError = false;
}
else if( (isNaN(currentValue)) && (ddd == "") )
{
alert("value must contain value in the textbox");
nonError = false;
}

parseint() will return a number if the string begins with one, even if there is non-numbers following it. For example: http://jsfiddle.net/uQztw/
Probably better to use a regex. Something like
http://jsfiddle.net/uQztw/1/

You can use regex to validate that. Using regex with jquery. And using regex
[\d]
which will match any digit should do the trick.

Another way to convert string to int is Number(ddd), it does what you expect. But you could also check ddd through a regular expression, which feels better to me.
regexp-test: /^\d+$/.test(ddd)

How to store more than 10 digit number in javascript using the var?

First of all,
What am i doing ?
I have to set the limit of emails in our product in webpage.It's handled with the javascript for validation.It handles upto 8 digit numbers fine. But in our QA team enters the more than 17 digit number in the text box of other email field.It throw the negative message.What can i do ???
My sample code is:
if(form.otherEmails) {
if(validEmailArray.endsWith(',')){
var otherEmailLength = validEmailArray.substring(0,validEmailArray.length-1).split(",");
var setLimitOtherEmail = window.parent.document.getElementById('setLimitOtherEmail').value;
if(setLimitOtherEmail == '-1'){
form.otherEmails.value = otherEmailLength;
}
else if(otherEmailLength.length <= setLimitOtherEmail){
form.otherEmails.value = otherEmailLength;
}
else{
alert("More than "+setLimitOtherEmail+ " " +"Recipient emailIds not allowed in this section.\nIf you want to send it to more recipients, Please create a Bulk Contact Group.");
form.otherEmails.focus();
return false;
}
}
else
form.otherEmails.value = validEmailArray;
}

This is due to the limit being a string, and when a string is being compared to a number (length) the number is coerced into a string, not the other way around.
These are then compared lexicographically - and lexicographically "9" is more (>) than "19".
You need to use parseInt(setLimitOtherEmail, 10) to get the value as a number before comparing them.

Try parsing each of the numbers into Integers before performing any comparison operations on them.
var setLimitOtherEmail = parseInt(window.parent.document.getElementById('setLimitOtherEmail').value);
Other than that are you certain otherEmailLength is actually the number that you want? From the looks of it you are taking the substring of validEmail array and splitting it on "," but it doesn't look like you actually get the length of the array. Try adding .length to the end of the value of otherEmailLength.
var otherEmailLength = validEmailArray.substring(0,validEmailArray.length-1).split(",").length;