数字键盘的 keyCode 值？

The keycodes are different. Keypad 0-9 is Keycode 96 to 105

Your if statement should be:

if ((e.keyCode >= 48 && e.keyCode <= 57) || (e.keyCode >= 96 && e.keyCode <= 105)) {
// 0-9 only
}

Here's a reference guide for keycodes

-- UPDATE --

This is an old answer and keyCode has been deprecated. There are now alternative methods to achieve this, such as using key:

if ((e.key >= 48 && e.key <= 57) || (e.key >= 96 && e.key <= 105)) {
// 0-9 only
}

Here's an output tester for event.key, thanks to @Danziger for the link.

You can simply run

$(document).keyup(function(e) {
console.log(e.keyCode);
});

to see the codes of pressed keys in the browser console.

Or you can find key codes here: https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/keyCode#Numpad_keys

You can use this to figure out keyCodes easily:

$(document).keyup(function(e) {
// Displays the keycode of the last pressed key in the body
$(document.body).html(e.keyCode);
});

http://jsfiddle.net/vecvc4fr/

keyCode is different for numbers on numeric keypad and numbers on top of keyboard.

keyCodes :

numbers on top of keyboard ( 0 - 9 ) : 48 - 57
numbers on numeric keypad ( 0 - 9 ) : 96 - 105

JavaScript condition :

if((e.keyCode >= 48 && e.keyCode <=57) || (e.keyCode >= 96 && e.keyCode <=105)) {
// entered key is a number
}

Reference for all keycodes ( with demo ) : http://www.codeforeach.com/javascript/keycode-for-each-key-and-usage-with-demo

******************* Don't use KEYCODE !!!! ******************

The problem with keyCode is to avoid the combined keys with the numbers on top of keyboard, we must add a check on the key "Shift" and "Alt" to avoid special characters such as e @ & " { } ...

A simplest solution is to convert e.key to a number and check if the conversion gives NaN!

let key = Number(e.key)
if (isNaN(key) || e.key === null || e.key === ' ') {
console.log("is not numeric")
}
else {
console.log("is numeric")
}

Be careful if e.key is null or a space, it gives 0 !

Number(5)         // => 5
Number('5')       // => 5
Number(null)      // => 0
Number(' ')       // => 0
Number('chars')   // => NaN
Number(undefined) // => NaN

For the people that want a CTRL+C, CTRL-V solution, here you go:

    /**
* Retrieves the number that was pressed on the keyboard.
*
* @param {Event} event The keypress event containing the keyCode.
* @returns {number|null} a number between 0-9 that was pressed. Returns null if there was no numeric key pressed.
*/
function getNumberFromKeyEvent(event) {
if (event.keyCode >= 96 && event.keyCode <= 105) {
return event.keyCode - 96;
} else if (event.keyCode >= 48 && event.keyCode <= 57) {
return event.keyCode - 48;
}
return null;
}

It uses the logic of the first answer.

The answer by @.A. Morel I find to be the best easy to understand solution with a small footprint. Just wanted to add on top if you want a smaller code amount this solution which is a modification of Morel works well for not allowing letters of any sort including inputs notorious 'e' character.

function InputTypeNumberDissallowAllCharactersExceptNumeric() {
let key = Number(inputEvent.key);
return !isNaN(key);
}

To add to some of the other answers, note that:

• keyup and keydown differ from keypress
• if you want to use String.fromCharCode() to get the actual digit from keyup, you'll need to first normalize the keyCode.

Below is a self-documenting example that determines if the key is numeric, along with which number it is (example uses the ABC0 function from lodash).

const isKeypad = range(96, 106).includes(keyCode);
const normalizedKeyCode = isKeypad ? keyCode - 48 : keyCode;
const isDigit = range(48, 58).includes(normalizedKeyCode);
const digit = String.fromCharCode(normalizedKeyCode);

You can use the key code page in order to find the:

event.code

to diference the number keyboard.

https://keycode.info/

function getNumberFromKeyEvent(event) {
if (event.code.indexOf('Numpad') === 0) {
var number = parseInt(event.code.replace('Numpad', ''), 10);
if (number >= 0 && number <= 9) {
// numbers from numeric keyboard
}
}
}

Yes, they are different and while many people have made a great suggestion of using console.log to see for yourself. However, I didn't see anyone mention event.location that you can use that to determine if the number is coming from the keypad event.location === 3 vs the top of the main keyboard / general keys event.location === 0. This approach would be best suited for when you need to generally determine if keystrokes are coming from a region of the keyboard or not, event.key is likely better for the specific keys.

Docs says the order of events related to the onkeyxxx event:

1. onkeydown
2. onkeypress
3. onkeyup

If you use like below code, it fits with also backspace and enter user interactions. After you can do what you want in onKeyPress or onKeyUp events. Code block trigger event.preventDefault function if the value is not number,backspace or enter.

onInputKeyDown = event => {
const { keyCode } = event;
if (
(keyCode >= 48 && keyCode <= 57) ||
(keyCode >= 96 && keyCode <= 105) ||
keyCode === 8 || //Backspace key
keyCode === 13   //Enter key
) {
} else {
event.preventDefault();
}
};

Little bit cleared @A.Morel's answer. You might beware of keyboard language layout. Some keyboard layouts changed default numeric keys to symbols.

let key = parseInt(e.key)
if (isNaN(key)) {
console.log("is not numeric")
}
else {
console.log("is numeric")
}