Javascript numberpad keycode parsing
Solution 1
You don't: you use the keypress
event. The keypress
event is the only event that will give you reliable information about typed characters. Your existing code will work if you simply change keydown
to keypress
.
Solution 2
The which
value passed to keydown
is not a character code; it's a key code (and the codes vary from browser/OS to browser/OS). You can map it to a character using the tables on this page, but to say that this stuff is a bit...awkward...would be to understate the case. :-)
Otherwise, your best bet is to wait for the keypress
event, which will have the character code (if relevant) rather than a key code.
Example: Live copy | Live source
jQuery(function($) {
$("#theField")
.keydown(function(event) {
showKey("keydown", event.which);
})
.keypress(function(event) {
showKey("keypress", event.which);
})
.focus();
function showKey(eventName, which) {
display(eventName +
": " + which + " (" +
String.fromCharCode(which) + ")");
}
function display(msg) {
$("<p>").html(msg).appendTo(document.body);
}
});
Using this HTML:
<input type="text" id="theField">
Solution 3
The answers here are now outdated because KeyboardEvent.which, KeyboardEvent.keyCode and KeyboardEvent.charCode are all deprecated.
The proper way for the latest versions of Firefox, Chrome, IE/Edge and Safari to obtain the character key is to use KeyboardEvent.key and it should work with any key event, not just keypress
.
KeyboardEvent.key Browser Compatibility
document.
querySelector('input').
addEventListener('keydown', event => console.log(event.key));
<input placeholder="Start typing...">
If you still need to obtain the character code, you should use the KeyboardEvent.code property.
KeyboardEvent.code Browser Compatibility
document.
querySelector('input').
addEventListener('keydown', event => console.log(event.code));
<input placeholder="Start typing...">
Solution 4
There is a way to do this with keydown, if keypress is not workable due to event canceling needs, etc. Use an if() statement with this test:
parseInt(event.keyIdentifier.substring(2),16) > 47 && parseInt(event.keyIdentifier.substring(2),16) < 58
OR, with jQuery events:
parseInt(event.originalEvent.keyIdentifier.substring(2),16) > 47 && parseInt(event.originalEvent.keyIdentifier.substring(2),16) < 58
These examples assume "event" is the keydown event. keyIdentifier is a hexidecimal number that represents the unicode value for the related char. Using keyIdentifier, numbers from the numberpad / keypad AND the numbers above your QWERTY keyboard will all have the same values, 48 - 57 (U+0030 - U+0039), even with the keyDown event.
Unicode values in the browsers will look like U+0030 or U+002F. Parse this string to only get the hexidecimal value, then use parseInt() with a radix of 16 to convert it to base-10.
Comments
-
Lee Quarella about 2 years
I am attempting to parse keydown events from the numberpad with the following:
$('#myDiv').keydown(function(e) { val = String.fromCharCode(e.which) });
The problem is that keypad
0-9
return keyCodes of96-105
which, according tofromCharCode()
are the lower case lettersa-i
. How do I get keydown events of the numberpad to resolve to the appropriate number?