Salesforce JavaScript Developer I Certification Practice Exam

Preventing default form submission in JavaScript is effectively achieved by calling `event.preventDefault()`. This method is specifically designed to stop the default action associated with the event that has occurred. When a form is submitted, it typically sends the data to the server. However, in scenarios where you want to handle the submission with JavaScript instead—such as validation checks or AJAX submissions—calling `event.preventDefault()` allows you to interrupt this automatic behavior.

This method should be invoked within an event handler, such as the `submit` event listener attached to the form. By implementing it, you can manage the form submission according to your specific needs without letting the browser execute the default submission process.

While returning false in an event handler might also prevent some default behaviors, it isn't as universally reliable or explicit as using `event.preventDefault()`, which is generally recommended for clarity and intent in modern JavaScript practices. The other options do not provide effective methods for controlling form submission behavior—different input types could influence how data is collected, and setting the action to 'void' would not prevent the form from submitting but would instead result in a navigation to a blank page potentially.