Keyboard input is an integral part of user interactivity on the web. Without proper handling of keyboard events, web applications would be cumbersome to use. In JavaScript, we can handle keyboard events with the help of Event.keyCode, which allows us to detect the key pressed by the user. Let's dive deeper into Event.keyCode and its usage in web development.
Understanding Event.keyCode
Event.keyCode is a numeric value that represents the code of the key pressed by the user. It is a read-only property of the event object used in keyboard events such as keydown, keyup or keypress. It can be used to detect the ASCII value of the pressed key, which can be further mapped to the actual character. For example, the ASCII value of the character 'A' is 65, and pressing the 'A' key on the keyboard will return the value 65 from Event.keyCode.
However, it's worth noting that not all keys have ASCII values. For non-printable keys such as the arrow keys or function keys, Event.keyCode returns a unique value instead of an ASCII value. Here is a list of some commonly used keys and their corresponding Event.keyCode values:
- Enter: 13
- Backspace: 8
- Tab: 9
- Arrow Up: 38
- Arrow Down: 40
- Escape: 27
- Shift: 16
- Ctrl: 17
- Alt: 18
Using Event.keyCode in Web Development
With Event.keyCode, we can create keyboard shortcuts or handle input from the user. For example, when the user presses the 'Enter' key in a form, we can submit the form data. Similarly, we can add listeners to any element on the web page to detect keyboard input using Event.keyCode.
Let's take an example of building a simple calculator that takes keyboard input from the user. We can use the keypress and keycode events to detect which key the user has pressed, and perform the corresponding calculation. Here's sample code for detecting the 'Enter' key press:
document.addEventListener(\"keypress\", function(event) {
if (event.keyCode === 13) {
// Do calculation
}
});Event.key: A Better Alternative to Event.keyCode
While Event.keyCode is a handy property to detect keyboard input, it has some limitations. For example, it doesn't work for input from non-letter keys such as those on international keyboards. Additionally, the API for keyboard input is constantly evolving to support more languages and layouts, and Event.keyCode may not be updated to support all these changes.
A better alternative is to use the Event.key property, which returns a human-readable string representation of the key pressed by the user. It provides better compatibility across different languages and layouts and works for non-letter keys as well. Here's an example code for detecting the 'Enter' key press using Event.key:
document.addEventListener(\"keydown\", function(event) {
if (event.key === \"Enter\") {
// Do calculation
}
});As you can see, using Event.key is more intuitive and robust than Event.keyCode, and it is the recommended property to use for detecting keyboard input in modern web development.
Conclusion
Event.keyCode and Event.key are important properties for handling keyboard input in web development. While Event.keyCode is a useful tool for detecting ASCII values of key inputs, Event.key provides better compatibility and language support. In most cases, using Event.key is recommended for better performance and user experience.