Which of the following expresses the conventional naming for event listener attributes in JSX?

Which of the following expresses the conventional naming for event listener attributes in JSX?

• A. onClick or onMouseOver or similar 'on' event
• B. onMouseOver style
• C. onEventName
• D. EventListener

Answer: (A)

In JSX, event handlers are written as attributes that start with on and use camelCase for the event name. The value of these attributes is a function. This convention lets the framework attach the handler to the corresponding DOM event behind the scenes. For example, onClick runs when the element is clicked, and onMouseOver runs when the mouse hovers over it. You can see it in a snippet like: <button onClick={handleClick} onMouseOver={handleHover}>Click me</button>. The other options don’t fit this pattern. OnMouseOver combined with style isn’t a valid single attribute—style is a separate prop. onEventName is too vague and doesn’t map to a real, concrete event you’d listen to in JSX. EventListener refers to the DOM API addEventListener, which is not how you declare event handlers in JSX.

In JSX, event handlers are written as attributes that start with on and use camelCase for the event name. The value of these attributes is a function. This convention lets the framework attach the handler to the corresponding DOM event behind the scenes. For example, onClick runs when the element is clicked, and onMouseOver runs when the mouse hovers over it. You can see it in a snippet like: Click me.

The other options don’t fit this pattern. OnMouseOver combined with style isn’t a valid single attribute—style is a separate prop. onEventName is too vague and doesn’t map to a real, concrete event you’d listen to in JSX. EventListener refers to the DOM API addEventListener, which is not how you declare event handlers in JSX.