We Keep Coding

Enter only digits in a textbox

I was using this function to enter only digits in to textbox and it worked.
function isNumberKey(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode > 31 && (charCode < 48 || charCode > 57))
return false;
return true;
}
but customer asked me to restrict - sign so user should not enter - sign. So I modified the code to this:
function isNumberKey(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode > 31 && (charCode < 48 || charCode > 57) && charCode == 45)
return false;
return true;
}
and now it not works, it allows letters too, why?

You need || in the group:
function isNumberKey(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode;
var bool = (charCode > 31) && (charCode < 48 || charCode > 57 || String.fromCharCode(charCode) == "-");
return !bool;
}
<input type="text" onkeypress='return isNumberKey(event)'>

You should use || instead of && in your test.
On my azerty keyboard, the - sign charcode is 54, not 45.
function isNumberKey(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode > 31 && (charCode < 48 || charCode > 57 || charCode == 45) )
return false;
return true;
}
See this fiddle
Edit
Looks like your charCode is correct. The 54 value comes from my azerty keyboard.
Nevertheless, you should use || instead of && in your check.

How my JS function would restrict specific data ?

In asp.net textbox I have called a javascript function which I wrote to restrict only 'digits' entry in text box but I also want to allow '+' sign but can't solve it.
This is what I have tried so far.
function isNumberKey(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode > 31 && (charCode < 48 || charCode > 57))
return false;
return true;
}

Just reverse your condition and add the ASCII code for + which is 43 to return true
function isNumberKey(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode
if ((charCode >=48 && charCode <= 57) || (charCode == 43))
return true;
return false;
}

If you were able to restrict digits, you can also enter '+', I guess you need ASCII table and corresponding value i.e. how you were restricting digits, and charCode > 31 seems useless if you are checking for digits only:
http://www.asciitable.com/
so if you want to check for +
charCode != 43

You need to check for + as well explicitly, modify your if to :
if (charCode > 31 && (charCode < 48 || charCode > 57) && charCode != 43)
Here is working example:
function isNumber(evt) {
evt = (evt) ? evt : window.event;
var charCode = (evt.which) ? evt.which : evt.keyCode;
if (charCode > 31 && (charCode < 48 || charCode > 57) && charCode != 43) {
return false;
}
return true;
}
<input type="text" class="textfield" value="" id="extra7" name="extra7" onkeypress="return isNumber(event)" />

Working Demo
Ascii Table
function isNumber(evt) {
evt = (evt) ? evt : window.event;
var charCode = (evt.which) ? evt.which : evt.keyCode;
if (charCode > 31 && (charCode < 48 || charCode > 57)&& charCode != 43) {
return false;
}
return true;
}

Javascript currency regular expression replace

For my business web application I want a user to only be able to enter valid currency values in a textbox.
Currently I use
$input.val($input.val().replace(/[^.\d]/g, ''));
But this doesn't take in consideration order or multiple decimal seperators.
So the user either has to enter a whole integer or a valid decimal value e.g.:
49
49.50
Bonus points if this is allowed too:
.50 (for 0.50)
So I don't want to validate, I want to restrict typing into the textbox. Is this possible with a single regexp replace?

We can do this in two steps. Restrict the user to type only the number characters and . character.
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode < 31 && (charCode > 48 || charCode < 57))
return true;
return false;
And the next one is for allowing the .:
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode == 46 && (charCode > 31 && (charCode < 48 || charCode > 57)))
return true;
return false;
The next step will be not allowing double periods.
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode == 46 && (charCode > 31 && (charCode < 48 || charCode > 57)))
if (charCode == 46 && value.indexOf(".") !== false)
return true;
return false;
Hope you can have this as a starting point.
Snippet
Open Deal: Break it if you can.
function check(inp) {
var charCode = (event.which) ? event.which : event.keyCode;
console.log(charCode);
if (charCode == 8)
return true;
if ((charCode > 46 && charCode < 58) || (charCode > 95 && charCode < 106) || charCode == 110 || charCode == 190)
if (charCode == 110 || charCode == 190)
if (inp.value.indexOf(".") == -1)
return true;
else
return false;
else
return true;
return false;
}
<input type="text" onkeydown="return check(this);" />

It's more user friendly to advise of errors and let users fix them themselves. You might consider using the keyup event, but showing an error too early (before the user has had a chance to enter a valid value) can be annoying too. e.g.
function validate(el) {
var type = el.className;
var errEl = document.getElementById(el.name + 'Err');
if (type == 'typeCurrency') {
var currencyRe = /^-?(\d+(\.\d{1,2})?|\.\d{1,2})$/;
errEl.style.visibility = currencyRe.test(el.value)? 'hidden' : 'visible';
}
}
.errorMessage {
color: red;
background-color: white;
visibility: hidden;
}
Cost <input onblur="validate(this)" name="foo" class="typeCurrency" placeholder="0.00"><br>
<span id="fooErr" class="errorMessage">Please enter a valid cost, e.g. 2.45</span>

Javascript validation works in Google Chrome but not in Firefox

Here is the js code
function isCharKey(evt){
var charCode = event.keyCode
if ((charCode > 64 && charCode <91 )|| (charCode >96 && charCode<123) || (charCode==32))
return true;
return false;
}
Here is the html code
<label id="exe_form_name">Name:</label><input type="text" name="tbcust_name" id="name1" onkeypress="return isCharKey(event);">

Change
var charCode = event.keyCode
to
var charCode = evt.keyCode

function isCharKey(evt)
{
var charCode = evt.keyCode
if ((charCode > 64 && charCode <91 )|| (charCode >96 && charCode<123) || (charCode==32))
return true;
return false;
}

how to define event below

I have a function below where it doesn't allow the user to type in letters in a textbox but it keeps saying event is undefined. Where and how am I suppose to define event?
Below is the function:
function isNumberKey(evt)
{
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode > 31 && (charCode < 48 || charCode > 57))
return false;
return true;
}
Below is the html where this could be used:
onkeypress="return isNumberKey(event)"

change
var charCode = (evt.which) ? evt.which : event.keyCode
to
var charCode = (evt.which) ? evt.which : evt.keyCode
or if you are using jQuery (you tagged it but aren't using it) you could do
$('#textareaid').keypress(function(e) {
if (e.which > 31 && (e.which < 48 || e.which > 57)) {
e.preventDefault();
}
});
where your html is
<textarea id="textareaid"></textarea>
See event.preventDefault()
Note on how to get key pressed using jQuery
To determine which character was entered, examine the event object
that is passed to the handler function. While browsers use differing
properties to store this information, jQuery normalizes the .which
property so you can reliably use it to retrieve the character code.
Taken from the .keypress() docs

here is the code which should work:
function checkerFunction(e){
var charCode=e.which || e.keyCode;
if(charCode<=31 || charCode>=48 && charCode<=57)return true;
return false;
}
and the event binding should be
onkeypress="return checkerFunction(window.event)"

For the record I think that most of the answers above don't take into consideration the ARROW keys.
This should be how it works incase you are googling this.
function isNumberKey(event)
{
var charCode = event.charCode;
if ((charCode < 48 || charCode > 57) && charCode != 0){
return false;
}
return true;
}