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jquery page prohibits page scrolling

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Release： 2023-05-14 09:58:37

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When developing web pages, we may encounter situations where we need to prohibit page scrolling under certain circumstances, such as pop-up modal boxes, pop-up menus, etc. In this case, we can use jQuery to disable page scrolling. The following will introduce in detail how to use jQuery to prevent page scrolling.

1. Obtaining and prohibiting scrolling

First, you need to obtain the scroll bar. We can use the following code to get the scroll bar:

var scrollTop = $(window).scrollTop();

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Among them, scrollTop() is the method used in jQuery to get the scroll bar position. After obtaining the value of scrollTop, we can use the following code to prohibit page scrolling:

$('body').addClass('noscroll').css({
   'top': -scrollTop + 'px'
 });

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Here, we added a custom class noscroll to the body element of the page, and set the top attribute to make the body element Move the position up to disable scrolling of the page. It should be noted that in order to avoid page flickering, when disabling page scrolling, the scrollTop value needs to be set to a negative number. Similarly, we can also use the following code to restore the scrolling of the page:

$('body').removeClass('noscroll');
$(window).scrollTop(scrollTop);

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Here, we remove the class noscroll for the body element of the page and use the scrollTop() method to set the scroll bar position back to the original value, so that scrolling of the page can be restored.

2. Avoid scroll bar width changes

After disabling page scrolling, a problem will arise: the disappearance of the scroll bar will cause the page width to shrink, which will cause page jitter. In order to solve this problem, we can add a placeholder element to the HTML structure. When the page scrolling is disabled, the width of the element is set to the width of the scroll bar of the current page, so as to avoid page shaking. The following is the code to add a placeholder element:

<body>
  <div class="scrollbar-width"></div>
  <!-- 页面其余结构 -->
</body>

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Next, we can use the following code to get the width of the scroll bar:

function getScrollbarWidth() {
  var outer = document.createElement('div');
  outer.style.visibility = 'hidden';
  outer.style.width = '100px';
  outer.style.msOverflowStyle = 'scrollbar'; // needed for WinJS apps
  document.body.appendChild(outer);
  var widthNoScroll = outer.offsetWidth;
  // force scrollbars
  outer.style.overflow = 'scroll';
  // add innerdiv
  var inner = document.createElement('div');
  inner.style.width = '100%';
  outer.appendChild(inner);        
  var widthWithScroll = inner.offsetWidth;
  // remove divs
  outer.parentNode.removeChild(outer);
  return widthNoScroll - widthWithScroll;
};

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Here, we use a function to get the width of the scroll bar width. First, a div element is created and styled to visibility: hidden and width: 100px. Then, set the msOverflowStyle style to the scrollbar (for WinJS applications) and append it to the document's body element. Next, use the innerWidth property to get the scroll bar width. Next, set the overflow style to scroll and create a new div element inner to fill the original div element outer. Finally, set the inner width to 100% and get its innerWidth. The last thing to do is to delete the div element and subtract the next width from the previous width to get the width of the scroll bar.

3. Complete code

Finally, we combine the codes introduced above to get the complete code to prohibit page scrolling:

var scrollbarWidth = getScrollbarWidth();
var scrollTop = $(window).scrollTop();

// 禁用滚动条
$('body').addClass('noscroll').css({
  'top': -scrollTop + 'px',
  'padding-right': scrollbarWidth + 'px'
});

// 恢复滚动条
$('body').removeClass('noscroll').css({
  'padding-right': ''
});
$(window).scrollTop(scrollTop);


function getScrollbarWidth() {
  var outer = document.createElement('div');
  outer.style.visibility = 'hidden';
  outer.style.width = '100px';
  outer.style.msOverflowStyle = 'scrollbar'; // needed for WinJS apps
  document.body.appendChild(outer);
  var widthNoScroll = outer.offsetWidth;
  // force scrollbars
  outer.style.overflow = 'scroll';
  // add innerdiv
  var inner = document.createElement('div');
  inner.style.width = '100%';
  outer.appendChild(inner);        
  var widthWithScroll = inner.offsetWidth;
  // remove divs
  outer.parentNode.removeChild(outer);
  return widthNoScroll - widthWithScroll;
};

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The above is to use jQuery to implement the prohibited page All steps for scrolling. With this method, we can better control the scrolling of the page when developing web pages and avoid some unexpected situations.

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