Develop Reference

jQuery method that disallows input of certain chars

I'm trying to make a jQuery method that would delete wanted chars from selected elements.
For example:
$("input").disallowChars(/\D/g);// should disallow input of all non-digit elements in input elements
This is how I thought to do it, but it doesn't seem to work:
$.fn.disallowChars = function(regexp){
this.keyup(function(){
var value = $(this).val();
value.replace(regexp, "");
$(this).val(value);
});
return this;
};
$("input").disallowChars(/\D/g);
I'm a total newbie at this, how can I make it work.
Thanks

You could use String.fromCharCode() and keypress event instead:
$.fn.disallowChars = function(regexp){
return this.keypress(function(e){
if(String.fromCharCode(e.which).match(regexp)) return false;
});
};
DEMO
BUT doesn't disable any characters to be paste in input using mouse or paste keyboard shortcut.
On modern browsers, you could use input event, or change keyup paste mouseup (ya mouseup, to handle dropped text too):
$.fn.disallowChars = function(regexp){
return this.on('input', function(){
this.value = this.value.replace(regexp, '');
});
};
BUT then once input value is replaced, text carret is put in end (or start depending browser behaviour) of string input.
DEMO

heres a handy routine I use to sanitize some input fields in a current project:
// REPLACE SELECTOR WITH YOUR ID(S) OR SELECTORS...
$('input').bind("change keyup", function() {
var val = $.trim($(this).val());
// READ UP ON REGEX TO UNDERSTAND WHATS GOING ON HERE... ADD CHARACTERS YOU WANT TO ELIMINATE...
var regex = /[":'/\+;<>&\\/\n]/g;
if (val.match(regex)) {
val = val.replace(regex, "");
$(this).val($.trim(val));
}
});
Heres another version I used recently:
$("#myField").on("keypress", function(event) {
// THIS ONLY ALLOWS A-Z, A-Z, 0-9 AND THE # SYMBOL... just change stuffToAllow to suit your needs
var stuffToAllow = /[A-Za-z0-9# ]/g;
var key = String.fromCharCode(event.which);
if (event.keyCode == 8 || event.keyCode == 37 || event.keyCode == 39 || stuffToAllow.test(key)) {
return true;
}
alert( key + ' character not allowed!');
return false;
});

How do I get key values in HTML/Javascript

Okay, so i understand how to get the key value while using an input field... but I am taking about key values that are pressed while your browser isn't focused in any text box or text area.
I am trying to make a onscreen keypad that has buttons for 0, 1, 2, .. 9... however I want the user to be able to press the buttons with the keys on the keyboard.
I've seen this done in some websites, where if you press the S key on the homepage, it will take you to the signin screen. Facebook also does the L key, to like a photo.
So the question is: How do I get the key values in javascript, when the cursor isn't focused.

If you are using JQuery you just add the event handler to the document...
$(document).keypress(function(event) {
alert('Handler for .keypress() called. - ' + event.which);
});
(From http://forum.jquery.com/topic/how-to-catch-keypress-on-body)
Edit for zzzzBov's comment...
From the JQuery KeyPress documentation:
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.

you need to use window.onkeydown and then check for the keys you're interested in.
https://developer.mozilla.org/en-US/docs/Web/API/window.onkeydown

You should listen on key press event.
document.onkeypress = function(evt) {
evt = evt || window.event;
var charCode = evt.which || evt.keyCode;
alert("Character typed: " + String.fromCharCode(charCode));
};
For more info Look here Link

You need to add an event listener to the window. Then in the event handler, you get the keyCode property from the passed-in event. KeyCodes are semi-arbitrary in that they don't directly map to what you might think, so you have to use a table (first result on google: http://www.cambiaresearch.com/articles/15/javascript-char-codes-key-codes) to identify the keycodes you care about.
window.addEventListener('keypress',function (evt) {
switch (evt.keyCode) {
case 48:
zeroKeyPressed(); break;
case 49:
oneKeyPressed(); break;
...
}
}, false);

You would use a key press event.
Here's an example for your usage:
window.addEventListener('keypress', function (event) {
var key_code, key;
event = event || window.event; // IE
key_code = event.charCode || event.keyCode || event.which || 0;
key = String.fromCharCode(key_code);
// prevent keys 0-9 from doing what they normally would do
if (key_code >= 48 && <= 57) {
event.preventDefault();
alert('The user pressed ' + key);
}
}, false);

Using plain js, you can use this in your layout.htmlcs, at the beginning:
#{
<script>
sessionStorage.setItem("ProductionHostURL", '#System.Configuration.ConfigurationManager.AppSettings["ProductionHostURL"]');
</script>
}
<!DOCTYPE html>
Then in your main js file of the layout.htmlcs, you can use this a method liked this:
var urlBaseProduction;
var urlBaseDevelopment;
$(document).ready(function () {
configureHostEnvironment()
....
}
In that method, configure the variables to use in production and development, like this:
function configureHostEnvironment(){
HOST = sessionStorage.getItem("ProductionHostURL")
if (HOST.length <= 0) {
alert("Host not configured correctly")
} else {
urlBaseProduction= host + '/api/';
urlBaseDevelopment= host + port + '/api/';
}
}
If you have a suggestion or improvement to this method, please comment.

Disable spaces in Input, AND allow back arrow?

I am trying to disable spaces in the Username text field, however my code disables using the back arrow too. Any way to allow the back arrow also?
$(function() {
var txt = $("input#UserName");
var func = function() {
txt.val(txt.val().replace(/\s/g, ''));
}
txt.keyup(func).blur(func);
});
fiddle: http://jsfiddle.net/EJFbt/

You may add keydown handler and prevent default action for space key (i.e. 32):
$("input#UserName").on({
keydown: function(e) {
if (e.which === 32)
return false;
},
change: function() {
this.value = this.value.replace(/\s/g, "");
}
});
DEMO: http://jsfiddle.net/EJFbt/1/

This seems to work for me:
<input type="text" onkeypress="return event.charCode != 32">

It doesn't "disable" the back arrow — your code keeps replacing all the text outright, whenever you press a key, and every time that happens the caret position is lost.
Simply don't do that.
Use a better mechanism for banning spaces, such as returning false from an onkeydown handler when the key pressed is space:
$(function() {
$("input#Username").on("keydown", function (e) {
return e.which !== 32;
});​​​​​
});
This way, your textbox is prohibited from receiving the spaces in the first place and you don't need to replace any text. The caret will thus remain unaffected.
Update
#VisioN's adapted code will also add this space-banning support to copy-paste operations, whilst still avoiding text-replacement-on-keyup handlers that affect your textbox value whilst your caret is still active within it.
So here's the final code:
$(function() {
// "Ban" spaces in username field
$("input#Username").on({
// When a new character was typed in
keydown: function(e) {
// 32 - ASCII for Space;
// `return false` cancels the keypress
if (e.which === 32)
return false;
},
// When spaces managed to "sneak in" via copy/paste
change: function() {
// Regex-remove all spaces in the final value
this.value = this.value.replace(/\s/g, "");
}
// Notice: value replacement only in events
// that already involve the textbox losing
// losing focus, else caret position gets
// mangled.
});​​​​​
});

Try checking for the proper key code in your function:
$(function(){
var txt = $("input#UserName");
var func = function(e) {
if(e.keyCode === 32){
txt.val(txt.val().replace(/\s/g, ''));
}
}
txt.keyup(func).blur(func);
});
That way only the keyCode of 32 (a space) calls the replace function. This will allow the other keypress events to get through. Depending on comparability in IE, you may need to check whether e exists, use e.which, or perhaps use the global window.event object. There are many question on here that cover such topics though.
If you're unsure about a certain keyCode try this helpful site.

One liner:
onkeypress="return event.which != 32"

Create an autocompleter like the Facebook status update

I'm trying to create a div with contenteditable like the Facebook status update. Then I mean I want to show an autocomplete box when the user have written #.
How would you do that. Currently I'm just playing with keypress and check if the keycode = 64. Somehow that works, but it doesn't validate if there's a space before the alfa, or if the user has unfocused the box, then focused it again.
Any ideas? Or do you know about any plugin that works something like that?
Tnx

I'd probably do it with keypress too.
but we need to check the cursor position to check the character before the '#'.
here's the function I used from http://javascript.nwbox.com/cursor_position/cursor.js
function getSelectionStart(o) {
if (o.createTextRange) {
var r = document.selection.createRange().duplicate();
r.moveEnd('character', o.value.length);
if (r.text == '') return o.value.length
return o.value.lastIndexOf(r.text);
} else {
return o.selectionStart;
}
}
then with jquery I wrote this keypress callback function:
txt.keypress(function(event) {
if (event.which == 64) {
var index = getSelectionStart(this)
var prevChar = txt.val().substring(index - 1, index);
// now you can check if the previous char was a space
}
});

How to REALLY limit the available character for an input field using jQuery?

I just started adding JS-validation to a signup form and I want the username input field in a Twitter-style (using jQuery). That means that the input is limited to certain characters and other characters do not even appear.
So far, I've got this:
jQuery(document).ready(function() {
jQuery('input#user_login').keyup(function() {
jQuery(this).val( jQuery(this).val().replace(/[^a-z0-9\_]+/i, '') );
});
});
This solution works, but the problem is that the illegal character appears as long as the user hasn't released the key (please excuse my terrible English!) and the keyup event isn't triggered. The character flickers in the input field for a second and then disappears.
The ideal solution would be the way Twitter does it: The character doesn't even show up once.
How can I do that? I guess I'll have to intercept the input in some way.

If you want to limit the characters the user may type rather than the particular keys that will be handled, you have to use keypress, as that's the only event that reports character information rather than key codes. Here is a solution that limits characters to just A-Z letters in all mainstream browsers (without using jQuery):
<input type="text" id="alpha">
<script type="text/javascript">
function alphaFilterKeypress(evt) {
evt = evt || window.event;
var charCode = evt.keyCode || evt.which;
var charStr = String.fromCharCode(charCode);
return /[a-z]/i.test(charStr);
}
window.onload = function() {
var input = document.getElementById("alpha");
input.onkeypress = alphaFilterKeypress;
};
</script>

Try using keydown instead of keyup
jQuery('input#user_login').keydown(function() {
Aside: You selector is slower than it needs to be. ID is unique, and fastest, so
jQuery('#user_login').keydown(function() {
Should suffice
You might want to consider capturing the keycode iself, before assigning it to the val
if (event.keyCode == ...)
Also, are you considering the alt, ctls, and shift keys?
if (event.shiftKey) {
if (event.ctrlKey) {
if (event.altKey) {

Thanks #TimDown that solved the issue! I modified your code a little so it accepts backspace and arrows for editing (I post a reply to use code formatting).
Thank you very much.
function alphaFilterKeypress(evt) {
evt = evt || window.event;
// START CHANGE: Allow backspace and arrows
if(/^(8|37|39)$/i.test(evt.keyCode)) { return; }
// END CHANGE
var charCode = evt.keyCode || evt.which;
var charStr = String.fromCharCode(charCode);
// I also changed the regex a little to accept alphanumeric characters + '_'
return /[a-z0-9_]/i.test(charStr);
}
window.onload = function() {
var input = document.getElementById("user_login");
input.onkeypress = alphaFilterKeypress;
};

You can use the maxlength property in inputs and passwords: info (that's actually the way Twitter does it).