What is the method to hide the scroll button when reaching the bottom?

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There are different ways to hide the scroll button when reaching the bottom, depending on the technology and tools used to create the website or application. Here are three possible methods:

1. CSS: One way to hide the scroll button when reaching the bottom is to use CSS to display the button only when the scroll position is not at the bottom. For example, one could use the "overflow" and "bottom" properties to set the maximum height of the scroll area and then apply a style to the button that sets its "display" property to "none" when the scroll position reaches the maximum height. Here's an example CSS rule:

#scroll-button {
  display: block;
}

#scroll-area {
  max-height: 500px; /* or some other value */
  overflow-y: scroll;
}

#scroll-area::-webkit-scrollbar-thumb {
  background-color: gray; /* or some other color */
}

#scroll-area::-webkit-scrollbar {
  width: 10px; /* or some other value */
}

#scroll-area::-webkit-scrollbar-track {
  background-color: white; /* or some other color */
}

#scroll-area:not(:at-bottom) + #scroll-button {
  display: block;
}

#scroll-area:at-bottom + #scroll-button {
  display: none;
}

In this example, the "scroll-area" element is the container that has the scrollbar, and the "scroll-button" element is the button that appears when the scrollbar is not at the bottom. The "::webkit-scrollbar" pseudo-elements are used to style the scrollbar itself. The ":at-bottom" and ":not(:at-bottom)" pseudo-classes are used to target the scroll position and apply the appropriate style to the button.

1. JavaScript: Another way to hide the scroll button when reaching the bottom is to use JavaScript to check the scroll position and toggle the visibility of the button accordingly. For example, one could add an event listener to the scroll container that checks if the scroll position is at the bottom, and then sets the "display" property of the button accordingly. Here's an example JavaScript code:

const scrollArea = document.querySelector('#scroll-area');
const scrollButton = document.querySelector('#scroll-button');

scrollArea.addEventListener('scroll', (event) => {
  if (event.target.scrollHeight - event.target.scrollTop === event.target.clientHeight) {
    scrollButton.style.display = 'none';
  } else {
    scrollButton.style.display = 'block';
  }
});

In this example, the "scrollArea" and "scrollButton" variables are assigned to the corresponding elements in the HTML. The "scroll" event listener is added to the "scrollArea" element, and inside it, the scroll position is checked by comparing the "scrollHeight", "scrollTop", and "clientHeight" properties of the element. If the scroll position is at the bottom, the "display" property of the button is set to "none", otherwise it is set to "block".

1. CSS + JavaScript: A third way to hide the scroll button when reaching the bottom is to combine the previous two methods by using CSS to set the initial style of the button and JavaScript to toggle it based on the scroll position. For example, one could use CSS to set the "display" property of the button to "none", and then use JavaScript to show it when the scroll position is not at the bottom. Here's an example code:

HTML:

<div id="scroll-area">
  <!-- content here -->
</div>

<button id="scroll-button">Scroll to top</button>

CSS:

#scroll-button {
  display: none;
}

#scroll-area {
  overflow-y: scroll; ...