Dynamically add new elements to the DOM and remove existing ones.
A key part of creating dynamic web applications is the ability to create and destroy HTML elements programmatically. JavaScript provides a straightforward API for this. To create a new element, you use the `document.createElement('tagName')` method, which returns a new, detached element object. For example, `document.createElement('div')` creates a new `<div>`. Once created, this element exists only in memory; it's not yet part of the page. You can then set its properties, like `textContent`, `className`, or add event listeners to it. To add the new element to the DOM, you need to append it to an existing element. The most common method is `parentElement.appendChild(newElement)`, which adds the new element as the last child of the parent. Other methods like `insertBefore` provide more control over placement. To remove an element, you can call `element.remove()`. This is a simple, modern method that removes the element directly from the DOM. An older, but still common, pattern is `element.parentNode.removeChild(element)`. Mastering the creation and removal of elements allows you to build user interfaces that respond to data, such as rendering a list of items from an API response or adding a new comment to a list without reloading the page.