I am performing alphanumeric validation and now I am doing that user can only enter an alphanumeric value and also allow alphanumeric values only while pasting. So I used the following regular expression
function OnlyAlphaNumeric(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode;
if ((charCode > 32 && charCode < 48) || (charCode > 57 && charCode < 65) ||
(charCode > 90 && charCode < 97) || charCode > 122) {
return false;
}
else {
return true;
}
}
And for preventing the copy and paste,
function CPOnlyAlphaNumeric(evt) {
$(evt).val($(evt).val().replace(/[^A-Za-z0-9]/g, ' '))
}
These two functions are calling from the following onkeypress and onkeyup methods such that is given below as shown that
#Html.TextBoxFor(model => model.ProductName, new { #class = "form-
control", #onkeypress = "return OnlyAlphaNumeric(this);", #onkeyup=
"return CPOnlyAlphaNumeric(this);" })
This works for alphanumeric validation, but it doesn't allow the cursor to move left side for editing the text. So what will change I should do in my Regular Expression.
Your problem has nothing related to regular expressions.
When you press any key (including left/right arrow) you take value of input, replace all forbidden characters and set the value of the input. When last action is done it's the browser native behavior to move the cursor to the end of input.
You can check what is the pressed key and if it's left/right arrow to skip the manipulation of input value.
function CPOnlyAlphaNumeric(evt) {
var code = evt.which ? evt.which : event.keyCode;
// 37 = left arrow, 39 = right arrow.
if(code !== 37 && code !== 39)
$(evt).val($(evt).val().replace(/[^A-Za-z0-9]/g, ' '))
}
Demo
However this is not a good solution because it will result in a terrible behavior (you won't be able to use shift for mark, the cursor will be moved at the end after first typed letter in the middle of word etc..)
A better solution could be to 'clean' the input value let's say 500 ms after user stop typing.
var timeout = null;
function CPOnlyAlphaNumeric(evt) {
if(timeout)
clearTimeout(timeout);
timeout = setTimeout(function(){
$(evt).val($(evt).val().replace(/[^A-Za-z0-9]/g, ' '))
}, 500);
}
Demo
Please note that you need to add the validation on server side as well (and maybe before the form submit, because user can hit enter to submit the form before the 'cleaning' of input is triggered).
You can try this, it may solve your problem.
var regex = new RegExp("^[a-zA-Z0-9]+$");
var charCode =(typeof event.which == "number") ?event.which:event.keyCode
var key = String.fromCharCode(charCode);
if (!(charCode == 8 || charCode == 0)) {
if (!regex.test(key)) {
event.preventDefault();
return false;
}
}
Problem with keyDown event is that you cant suppress the display of keys in the textfield (only alpha numeric in my case). You can do it in only keyPress event. But you cant get navigation keys in keyPress event, you can only track them in KeyDown event. And some of the keys $,%, have the same e.which that arrow keys has in keypress event. which is causing issues for me to write the logic to allow arrow keys but restrict the text to only Alpha numeric. Here is the code I came up with. Working fine now.
onKeyPress: function(e){
var regex = new RegExp("^[a-zA-Z0-9\b ]+$");
var str = String.fromCharCode(!e.charCode ? e.which : e.charCode);
var allowedSpecialKeys = 'ArrowLeftArrowRightArrowUpArrowDownDelete';
var key = e.key;
/*IE doesn't fire events for arrow keys, Firefox does*/
if(allowedSpecialKeys.indexOf(key)>-1){
return true;
}
if (regex.test(str)) {
return true;
}
e.preventDefault();
e.stopPropagation();
e.cancelBubble = true;
return false;
}
Related
I have been using jquery to capture the keydown event and validate the entered text for different cases like: characters only, alpha-numeric, characters and spaces etc.
Regex used:
Characters with spaces: ^[a-zA-Z ]+$
Characters only: ^[a-zA-Z]+$
Alphanumerics: ^[a-zA-Z0-9]+$
This is how I am using the bind function:
$('.chars_and_space_only').bind('keydown', function (event) {
// http://stackoverflow.com/a/8833854/260665
var eventCode = !event.charCode ? event.which : event.charCode;
if((eventCode >= 37 && eventCode <= 40) || eventCode == 8 || eventCode == 9 || eventCode == 46) { // Left / Right Arrow, Backspace, Delete keys
return;
}
// http://stackoverflow.com/a/8833854/260665
var regex = new RegExp("^[a-zA-Z ]+$");
var key = String.fromCharCode(eventCode);
if (!regex.test(key)) {
event.preventDefault();
return false;
}
});
All of above uses cases are working fine, however I have to now include characters, spaces, apostrophe and periods. So this is the method I have modified:
$(".chars_space_dots_apostrophes_only").bind('keydown', function (event) {
// http://stackoverflow.com/a/8833854/260665
var eventCode = !event.charCode ? event.which : event.charCode;
if((eventCode >= 37 && eventCode <= 40) || eventCode == 8 || eventCode == 9 || eventCode == 46) { // Left / Right Arrow, Backspace, Delete keys
return;
}
// http://stackoverflow.com/a/8833854/260665
var regex = new RegExp("^[a-zA-Z '.]+$");
var key = String.fromCharCode(eventCode);
if (!regex.test(key)) {
event.preventDefault();
return false;
}
});
This, strangely doesn't seem to work. Here is the fiddle: https://jsfiddle.net/ugu8f4y3/
Regex used: ^[a-zA-Z '.]+$
Regex validator does validate this text for the above regex:
Hello. World's
But the text field in fiddle does not allow me to enter periods and apostrophes, is there something I am missing here?
The problem is with jquery and the keydown event. Replace it with keypress and you'll be good to go. You should also only need to check in which.
keydown and keyup are important for cases when you're concerned with the position of the key's physical location. In this case you want to know that the key was depressed and handle the resulting input. jquery will normalize the character codes differently.
Further information about the differences between keypress, keydown and key up.
Updated Fiddle
I have use this code for allow numeric only in textbox, but how make Charkey only allow AlphaNumeric and other symbol like -./ (dash,dot,slash)
this my code for allow Numeric
function NumericKey(evt){
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode > 31 && (charCode < 48 || charCode > 57))
return false;
return true;
}
thankyou
Firstly, Character Codes and Key Codes are different thing, what you're looking for is Key Codes.
You can first check the key codes you want to allow/disallow by looking them up in a online table, or here: http://keycode.info/
Then then by using a whitelist/blacklist to check the codes:
function NumericKey(evt){
var allowed = [189, 190, 191]; // corresponds to **. , -**
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode > 31 && (charCode < 48 || charCode > 57))
return allowed.indexOf(charCode) >= 0;
return true;
}
This would allow you to arbitrarily whitelist any keycodes.
A simpler solution to your case, since key codes of ,.- are adjacent to each other:
function NumericKey(evt){
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode > 31 && (charCode < 48 || charCode > 57) && !(charCode >= 189 && charCode <= 191))
return false;
return true;
}
You should not listen for keyboard events (keydown / keypress / keyup) to filter out certain characters, as the value of the input can also be updated by pasting or dropping text into it and there are many exceptions you should not prevent, such as arrows, delete, escape, shortcuts such as select all, copy, paste... so trying to come up with an exhaustive list of the ones that should be allowed is probably not a good idea.
Moreover, that won't work on mobile, where most keys emit the same values e.key = 'Unidentified', e.which== 229 and e.keyCode = 229.
Instead, just listen for the input event and update the input value removing all invalid characters while preserving the cursor's position:
const input = document.getElementById('input');
input.oninput = (e) => {
const cursorPosition = input.selectionStart - 1;
const hasInvalidCharacters = input.value.match(/[^0-9 -./]/);
if (!hasInvalidCharacters) return;
// Replace all non-digits:
input.value = input.value.replace(/[^0-9 -./]/g, '');
// Keep cursor position:
input.setSelectionRange(cursorPosition, cursorPosition);
};
<input id="input" type="text" placeholder="Digits and - . / only" />
Here you can see a similar answer and example for a slightly more complex behaviour to allow only numbers with one single decimal separator: https://stackoverflow.com/a/64084513/3723993
Anyway, if you still want to try that approach, just keep in mind both e.which and e.keyCode are deprecated, so e.key or e.code should be used instead, which also makes the code easier to understand. Also keep in mind some old browsers used some non-standard codes for some keys, so, for example, left is usually 'LeftArrow' and right is 'RightArrow', but on IE and Legacy Edge they would be 'Left' and 'Right' instead.
If you need to check KeyboardEvent's properties values such as e.key, e.code, e.which or e.keyCode you can use https://keyjs.dev. I will add information about these kinds of cross-browser incompatibilities soon!
Disclaimer: I'm the author.
I have the following validation to allow only numbers and a decimal in Javascript
function validate(evt) {
var theEvent = evt || window.event;
var key = theEvent.keyCode || theEvent.which;
key = String.fromCharCode( key );
var regex = /[0-9]|\./;
if( !regex.test(key) ) {
theEvent.returnValue = false;
if(theEvent.preventDefault) theEvent.preventDefault();
}
}
I call this in my textbox element like onkeypress='validate(event)'
This code works fine in IE but when I try the same with Firefox backspace, left and right arrow keys and space does not work.
How would I fix this?
Using key press is the right solution, but you simply need to attach the event handler by JS (which is considered better practice anyway), and use something like this:
$('#myInput').keypress(function(event){
validate(event)
});
function validate(evt) {
var theEvent = evt || window.event;
var key = theEvent.keyCode || theEvent.which;
if (key <48 || key > 57 || key == 190)//keycode is a number between 0 and 9 or '.'
...
};
use keyup or keydown instead of keypress
keypress is only supposed to fire when there is a character insert
http://www.quirksmode.org/dom/events/keys.html
keydown function would work across all browsers. Please use keydown function and it would work!
Ex.:-
$(document).keydown(function (e){
if(e.keyCode == 37) // left arrow
{
//code for left arrow
}
else if(e.keyCode == 39) // right arrow
{
//code for right arrow
}
});
Try
//allows number and hyphen only
function isNumeric(e)
{
var a = e.charCode;
if(a==0){return;}
return ((a >= 48 && a <= 57));
}
</script>
Firefox Backspace charcode 0.
I'm trying to build a communal wall, that appears the same for all those who access the web page, and syncs between users. I'm struggling to capture keyboard input correctly to apply to the canvas. My function is based on document.onkeydown, and can be seen in the 'script.js' referenced in the said web page. It can be seen working when you double click a word and the write.
Unfortunately this seems to be failing to capture anything but capital letters, and I'm looking for an alternate way to go about this. I've looked into the 'textInput' event, described in this page, however it seems to be only supported by WebKit browsers, and I want to build something which works generically. Can someone suggest an alternate way to go about capturing keyboard input for use in canvas? Or perhaps I'm doing something silly?
Code described is here:
document.onkeydown = keyHandler;
function keyHandler(e)
{
var pressedKey;
if (document.all) { e = window.event;
pressedKey = e.keyCode; }
if (e.which) {
pressedKey = e.which;
}
if (pressedKey == 8) {
e.cancelBubble = true; // cancel goto history[-1] in chrome
e.returnValue = false;
}
if (pressedKey == 27)
{
// escape key was pressed
keyCaptureEdit = null;
}
if (pressedKey != null && keyCaptureEdit != null)
{
keyCaptureEdit.callback(pressedKey);
}
}
... Later on in code describing each text object ...
keyCaptureEdit.callback = function (keyCode) {
var keyCaptured = String.fromCharCode(keyCode);
if (keyCaptured == "\b" ) { //backspace character
t.attrs.timestamp = t.attrs.timestamp + 1;
t.setText(t.getText().slice(0, -1));
}
else if (keyCode == 32 || keyCode >= 48 && keyCode <= 57 || keyCode >= 65 && keyCode <= 90)
{
t.attrs.timestamp = t.attrs.timestamp + 1;
t.setText(t.getText() + keyCaptured);
}
layer.draw();
}
Well one trivial way to change your code would be to keep track of the shift key:
...
{
keyCaptureEdit.callback(pressedKey, e.shiftKey); // <-- keep track of shift key
}
}
...
keyCaptureEdit.callback = function (keyCode, shift) {
var keyCaptured = String.fromCharCode(keyCode);
// shift key not pressed? Then it's lowercase
if (shift === false) keyCaptured = keyCaptured.toLowerCase()
But that doesn't account for CapsLock.
In jQuery its really simple because the right key code is done for you:
$(document).keypress(function(event) {
var keyCaptured = String.fromCharCode(event.keyCode);
console.log(keyCaptured);
});
In that example the console will correctly log P or p depending on what would be typed.
I am wondering how to create an event listener, so that when any of the character keys are pressed a form pops up and the first input is in focus and is receiving the input, sort of like the just type search style for the webOS 2.0 operating system, but for a contact form. Is there anyway to do so? In case your not familiar here is a link to the webos just type feature
http://www.youtube.com/watch?v=ixPsB7-tVGo
I don't know if you can only subscribe to letter keys.
Your best bet would be to use jQuery to subscribe to .keydown() / .keyup() and check the keycode of the event to see which letter it is. If it's not a letter, don't do anything.
Like this:
$('#target').keydown(function(event) {
if (event.keyCode >= 65 && event.keyCode <= 90) { // if a letter pressed
// play that funky music.
}
});
More on $.keydown.
List of key codes.
Use the keypress event for anything character related. keydown and keyup cannot be used reliably for this purpose. The following is adapted from my answer to a related recent question:
function isCharacterKeyPress(evt) {
if (typeof evt.which == "undefined") {
// This is IE, which only fires keypress events for printable keys
return true;
} else if (typeof evt.which == "number" && evt.which > 0) {
// In other browsers except old versions of WebKit, evt.which is
// only greater than zero if the keypress is a printable key.
// We need to filter out backspace and ctrl/alt/meta key combinations
return !evt.ctrlKey && !evt.metaKey && !evt.altKey && evt.which != 8;
}
return false;
}
var input = document.getElementById("your_input_id");
input.onkeypress = function(evt) {
evt = evt || window.event;
if (isCharacterKeyPress(evt)) {
// Do your stuff here
alert("Character!");
}
};