What Does `return false` in a JavaScript Click Event Listener Do?

Impact of Adding 'return false' to Click Event Listener

In many HTML documents, you may encounter links that include 'return false' in their onclick event listeners, as seen below:

<a href='#' onclick='someFunc(3.1415926); return false;'>Click here !</a>

This 'return false' statement plays a crucial role in modifying the default browser behavior upon clicking the link.

The return value of an event handler determines whether the standard browser action should occur in addition to the custom code specified in the event listener. In the case of link clicks, the default action is navigating to the specified URL. However, adding 'return false' prevents this default behavior, ensuring that the link only executes the custom function defined in the onclick attribute.

This technique is commonly used to prevent the page from reloading unnecessarily, as in the case of form submissions. By returning false within the submit button's onclick event listener, you can validate the user's input before submitting the form, preventing potential errors and improving user experience.

While the DOM 0 specification does not explicitly mention this behavior, it can be inferred from the general concept of event handling. The modern approach to achieve the same effect is to utilize event.preventDefault(), which is part of the DOM 2 Events specification.

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