Keyboard shortcuts in JavaScript
Keyboard shortcuts in JavaScript can be implemented using the
keydown
or keyup
events to listen for specific key presses. Here's a guide to creating and handling keyboard shortcuts: ---
### **Basic Syntax**
```javascript
document.addEventListener('keydown', function(event) {
if (event.key === 'Control' && event.key === 's') {
event.preventDefault(); // Prevent the default browser behavior
console.log('Ctrl+S was pressed!');
}
});
```
### **Key Properties**
- `event.key`: The actual key value (e.g., `'a'`, `'Enter'`).
- `event.code`: Physical key on the keyboard (e.g., `'KeyA'` for the 'A' key).
- `event.altKey`: Returns `true` if the `Alt` key is pressed.
- `event.ctrlKey`: Returns `true` if the `Ctrl` key is pressed.
- `event.shiftKey`: Returns `true` if the `Shift` key is pressed.
- `event.metaKey`: Returns `true` if the `Meta` key (Command key on Mac) is pressed.
---
### **Example 1: Simple Shortcut (Ctrl + S)**
```javascript
document.addEventListener('keydown', function(event) {
if (event.ctrlKey && event.key === 's') {
event.preventDefault(); // Prevent default browser save
console.log('Custom save action triggered!');
// Add your custom logic here
}
});
```
---
### **Example 2: Multiple Shortcuts**
```javascript
document.addEventListener('keydown', function(event) {
if (event.ctrlKey && event.key === 'z') {
console.log('Undo action triggered!');
} else if (event.ctrlKey && event.key === 'y') {
console.log('Redo action triggered!');
} else if (event.altKey && event.key === 'Enter') {
console.log('Alt+Enter triggered!');
}
});
```
---
### **Example 3: Customizable Key Bindings**
```javascript
const shortcuts = {
'Ctrl+S': () => console.log('Save action triggered!'),
'Ctrl+Z': () => console.log('Undo action triggered!'),
'Ctrl+Shift+N': () => console.log('New file created!'),
};
document.addEventListener('keydown', function(event) {
const keyCombination =
(event.ctrlKey ? 'Ctrl+' : '') +
(event.shiftKey ? 'Shift+' : '') +
event.key.toUpperCase();
if (shortcuts[keyCombination]) {
event.preventDefault(); // Optional: Prevent default behavior
shortcuts[keyCombination]();
}
});
```
---
### **Example 4: Key Sequence Tracking**
For tracking sequences like "Shift + A, then B":
```javascript
let sequence = [];
const targetSequence = ['Shift+A', 'B'];
document.addEventListener('keydown', function(event) {
const key = (event.shiftKey ? 'Shift+' : '') + event.key.toUpperCase();
sequence.push(key);
if (sequence.length > targetSequence.length) {
sequence.shift();
}
if (JSON.stringify(sequence) === JSON.stringify(targetSequence)) {
console.log('Sequence Shift+A -> B detected!');
sequence = []; // Reset sequence
}
});
```
---
### **Example 5: Disabling Specific Shortcuts**
To disable browser shortcuts (e.g., `Ctrl+P` or `Ctrl+S`):
```javascript
document.addEventListener('keydown', function(event) {
if (event.ctrlKey && ['p', 's'].includes(event.key.toLowerCase())) {
event.preventDefault();
console.log(`Blocked Ctrl+${event.key.toUpperCase()}`);
}
});
```
---
### **Notes**
1. **Cross-Browser Compatibility**: Key codes (`event.code`) might vary for certain keys (like function keys) across browsers.
2. **Prevent Default Behavior**: Use `event.preventDefault()` to avoid triggering default browser actions (e.g., saving, refreshing).
3. **Debouncing**: If necessary, add a delay to prevent multiple triggers from holding down a key.
4. **Accessibility**: Avoid overriding shortcuts essential for accessibility (e.g., `Ctrl+Shift+N` in screen readers).
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