Quiz Entry - updated: 2026.07.14
What are the two ways to attach event handlers in JavaScript?
You can attach handlers declaratively with an HTML on... attribute or programmatically in JavaScript (preferably addEventListener).
1. Declarative (HTML attribute):
<button onclick="handleClick()">Click me</button>
<input oninput="validate(this.value)">
2. Programmatic (JavaScript):
// addEventListener (preferred)
button.addEventListener("click", handleClick);
// Direct property assignment
button.onclick = handleClick;
Comparison:
| Aspect | Declarative | Programmatic |
|---|---|---|
| Multiple handlers | No | Yes (addEventListener) |
| Separation of concerns | Poor | Good |
| Dynamic elements | Difficult | Easy |
| Remove handler | Difficult | Easy |
Best practice: Use addEventListener for clean separation of HTML and JavaScript.