Prevent automatic scrolling by clicking when you reach the bottom

Question

Prevent automatic scrolling by clicking when you reach the bottom

In order to replicate the issue I am experiencing, please click on the down button four times, and then click on the up button. You will observe that you need to click the up button one extra time for it to function properly. How can I detect when it has reached the bottom and return false?

var scrollValue = 0;
$('#down').click(function(){
      scrollValue = scrollValue + 180;
    $('ul').animate({scrollTop:scrollValue});
});

$('#up').click(function(){
      scrollValue = scrollValue + -180;
    $('ul').animate({scrollTop:scrollValue});
});

ul {
  padding: 0;
  margin: 0;
  height: 180px;
  overflow: auto;
}
li {
  height: 50px;
  background: pink;
  list-style: none;
  margin-bottom: 10px;
  height: 50px;
}
body {
  padding: 0;
  margin: 0;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<ul>
  <li>1</li>
  <li>2</li>
  <li>3</li>
  <li>4</li>
  <li>5</li>
  <li>6</li>
  <li>7</li>
  <li>8</li>
  <li>9</li>
  <li>10</li>
</ul>
<button id="up">up</button>
<button id="down">down</button>

javascript jquery html css

Answer 1

Answer №1

To achieve the desired behavior, it is essential to consider the container height using 'scrollHeight'. If the scroll position exceeds the height or tries to go below 0, it should be adjusted accordingly.

var scrollValue = 0;
var nHeight = $('ul').height();
var height = $('ul').prop('scrollHeight');
height = height - nHeight;

$('#down').click(function(){
      var nScrollValue = scrollValue + 180;
      if(nScrollValue < height){
         scrollValue = nScrollValue;
      } else {
         scrollValue = height;
      }
      $('ul').animate({scrollTop:scrollValue});
});

$('#up').click(function(){
      var nScrollValue = scrollValue - 180;
      if(nScrollValue > 0){
        scrollValue = nScrollValue;
      } else {
        scrollValue = 0;
      }
      $('ul').animate({scrollTop:scrollValue});
});

I recommend utilizing jQuery to facilitate scrolling actions without manually tracking 'scrollValue':

$('#down').click(function(){
      $('ul').animate({scrollTop: '+=180'});
});

$('#up').click(function(){
      $('ul').animate({scrollTop: '-=180'})
});

Answer 2

To achieve the desired behavior, it is essential to consider the container height using 'scrollHeight'. If the scroll position exceeds the height or tries to go below 0, it should be adjusted accordingly.

var scrollValue = 0;
var nHeight = $('ul').height();
var height = $('ul').prop('scrollHeight');
height = height - nHeight;

$('#down').click(function(){
      var nScrollValue = scrollValue + 180;
      if(nScrollValue < height){
         scrollValue = nScrollValue;
      } else {
         scrollValue = height;
      }
      $('ul').animate({scrollTop:scrollValue});
});

$('#up').click(function(){
      var nScrollValue = scrollValue - 180;
      if(nScrollValue > 0){
        scrollValue = nScrollValue;
      } else {
        scrollValue = 0;
      }
      $('ul').animate({scrollTop:scrollValue});
});

I recommend utilizing jQuery to facilitate scrolling actions without manually tracking 'scrollValue':

$('#down').click(function(){
      $('ul').animate({scrollTop: '+=180'});
});

$('#up').click(function(){
      $('ul').animate({scrollTop: '-=180'})
});

Answer 3

Answer №2

Give this a shot:

$(document).ready(function() {
    var scrollAmount = 0;
    numCases = ($("li").length/3)-1; // 3 represents the number of visible rows
    $('#down').click(function(){
        if(scrollAmount <= (numCases*180)  ){
            scrollAmount = scrollAmount + 180;
            console.log(scrollAmount)
            $('ul').animate({scrollTop:scrollAmount});
        }
    });

    $('#up').click(function(){
        if(scrollAmount >= (180)  ){
            scrollAmount = scrollAmount + -180;
            $('ul').animate({scrollTop:scrollAmount});
        }
    });
})

ul {
  padding: 0;
  margin: 0;
  height: 180px;
  overflow: auto;
}
li {
  height: 50px;
  background: pink;
  list-style: none;
  margin-bottom: 10px;
  height: 50px;
}
body {
  padding: 0;
  margin: 0;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul>
  <li>1</li>
  <li>2</li>
  <li>3</li>
  <li>4</li>
  <li>5</li>
  <li>6</li>
  <li>7</li>
  <li>8</li>
  <li>9</li>
  <li>10</li>
</ul>
<button id="up">up</button>
<button id="down">down</button>

Answer 4

Give this a shot:

$(document).ready(function() {
    var scrollAmount = 0;
    numCases = ($("li").length/3)-1; // 3 represents the number of visible rows
    $('#down').click(function(){
        if(scrollAmount <= (numCases*180)  ){
            scrollAmount = scrollAmount + 180;
            console.log(scrollAmount)
            $('ul').animate({scrollTop:scrollAmount});
        }
    });

    $('#up').click(function(){
        if(scrollAmount >= (180)  ){
            scrollAmount = scrollAmount + -180;
            $('ul').animate({scrollTop:scrollAmount});
        }
    });
})

ul {
  padding: 0;
  margin: 0;
  height: 180px;
  overflow: auto;
}
li {
  height: 50px;
  background: pink;
  list-style: none;
  margin-bottom: 10px;
  height: 50px;
}
body {
  padding: 0;
  margin: 0;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul>
  <li>1</li>
  <li>2</li>
  <li>3</li>
  <li>4</li>
  <li>5</li>
  <li>6</li>
  <li>7</li>
  <li>8</li>
  <li>9</li>
  <li>10</li>
</ul>
<button id="up">up</button>
<button id="down">down</button>

Answer 5

Answer №3

One way to determine the height of the document before animating the page scroll is by comparing it with the current scroll position

var documentHeight = $(document).height();

This will give you the total height of your document. If the animation occurs within a specific element, simply replace $(document) with that element

To check if the scroll has reached the bottom, use the following code snippet

if(scrollValue + 180 > documentHeight) {
    // At the bottom
}

Answer 6

One way to determine the height of the document before animating the page scroll is by comparing it with the current scroll position

var documentHeight = $(document).height();

This will give you the total height of your document. If the animation occurs within a specific element, simply replace $(document) with that element

To check if the scroll has reached the bottom, use the following code snippet

if(scrollValue + 180 > documentHeight) {
    // At the bottom
}

Answer 7

Answer №4

Prior to adjusting your scrollValue variable by adding or subtracting 180, it is important to verify if it is already at the edge.

Here is the JavaScript code snippet:

var scrollValue = 0;
$('#down').click(function(){
      if (scrollValue < $(ul).height() ) {
          scrollValue = scrollValue + 180;
          $('ul').animate({scrollTop:scrollValue});
      }
});

$('#up').click(function(){
      if (scrollValue > 0) {
          scrollValue = scrollValue - 180;
          $('ul').animate({scrollTop:scrollValue});
      }
});

While I'm not entirely certain if the comparisons are accurate, perhaps comparing to a value other than $(ul).height() could be more appropriate. Nonetheless, this approach seems to be on the right track.

Answer 8

Prior to adjusting your scrollValue variable by adding or subtracting 180, it is important to verify if it is already at the edge.

Here is the JavaScript code snippet:

var scrollValue = 0;
$('#down').click(function(){
      if (scrollValue < $(ul).height() ) {
          scrollValue = scrollValue + 180;
          $('ul').animate({scrollTop:scrollValue});
      }
});

$('#up').click(function(){
      if (scrollValue > 0) {
          scrollValue = scrollValue - 180;
          $('ul').animate({scrollTop:scrollValue});
      }
});

While I'm not entirely certain if the comparisons are accurate, perhaps comparing to a value other than $(ul).height() could be more appropriate. Nonetheless, this approach seems to be on the right track.

Answer 9

Answer №5

Make sure to check if the scrollValue is equal to or greater than 0 for it to function properly. Refer to the snippet below.

var scrollValue = 0;
$('#down').click(function(){
      if(scrollValue >= 0){
         scrollValue = scrollValue + 180;
      }
    $('ul').animate({scrollTop:scrollValue});
});

$('#up').click(function(){
    scrollValue = scrollValue + -180;
    $('ul').animate({scrollTop:scrollValue});
});

ul {
  padding: 0;
  margin: 0;
  height: 180px;
  overflow: auto;
}
li {
  height: 50px;
  background: pink;
  list-style: none;
  margin-bottom: 10px;
  height: 50px;
}
body {
  padding: 0;
  margin: 0;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<ul>
  <li>1</li>
  <li>2</li>
  <li>3</li>
  <li>4</li>
  <li>5</li>
  <li>6</li>
  <li>7</li>
  <li>8</li>
  <li>9</li>
  <li>10</li>
</ul>
<button id="up">up</button>
<button id="down">down</button>

Answer 10

Make sure to check if the scrollValue is equal to or greater than 0 for it to function properly. Refer to the snippet below.

var scrollValue = 0;
$('#down').click(function(){
      if(scrollValue >= 0){
         scrollValue = scrollValue + 180;
      }
    $('ul').animate({scrollTop:scrollValue});
});

$('#up').click(function(){
    scrollValue = scrollValue + -180;
    $('ul').animate({scrollTop:scrollValue});
});

ul {
  padding: 0;
  margin: 0;
  height: 180px;
  overflow: auto;
}
li {
  height: 50px;
  background: pink;
  list-style: none;
  margin-bottom: 10px;
  height: 50px;
}
body {
  padding: 0;
  margin: 0;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<ul>
  <li>1</li>
  <li>2</li>
  <li>3</li>
  <li>4</li>
  <li>5</li>
  <li>6</li>
  <li>7</li>
  <li>8</li>
  <li>9</li>
  <li>10</li>
</ul>
<button id="up">up</button>
<button id="down">down</button>

Prevent automatic scrolling by clicking when you reach the bottom

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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