evt.preventDefault vs evt.stopPropagation

 

evt.preventDefault()` and `evt.stopPropagation()` are both methods commonly used in JavaScript to control event propagation and behavior.

1. `evt.preventDefault()`: This method is used to prevent the default behavior of an event. In many cases, when an event (such as a click or form submission) occurs, the browser executes some default behavior associated with that event. For example, clicking on a link navigates the browser to the URL specified in the link's `href` attribute. By calling `evt.preventDefault()` inside an event handler function, you can prevent this default behavior from occurring. This is useful when you want to handle an event in a custom way, such as submitting a form via Ajax instead of the default form submission behavior.

2. `evt.stopPropagation()`: This method is used to stop the propagation of an event through the DOM tree. When an event occurs on an element, it typically "bubbles" up through the DOM tree, triggering event handlers on ancestor elements. By calling `evt.stopPropagation()`, you prevent the event from propagating any further in the DOM tree. This means that event handlers on parent elements will not be executed. This is useful when you want to handle an event on a specific element without triggering event handlers on its ancestors.

In summary, `evt.preventDefault()` is used to prevent the default behavior of an event, while `evt.stopPropagation()` is used to stop the event from propagating further through the DOM tree. Both methods are commonly used together to control event behavior in JavaScript applications.