Question

请在整个页面中运行该代码段。我正在尝试使用偏移功能。但是我在这里面临一些问题。偏移函数在悬停时返回0，但在悬停时返回实数值。因此，当元素显示在屏幕上时，我没有获得真正的价值。显示元素时如何获得实际价值？

$('ul.nav li.dropdown').hover(function() {
  $(this).find('.dropdown-menu').stop(true, true).delay(200).fadeIn(500);
}, function() {
  $(this).find('.dropdown-menu').stop(true, true).delay(200).fadeOut(500);
});

$('.dropdown-toggle').parent().hover(function() {
    var menu = $(this).find("ul");
    var menupos = $(menu).offset();
    console.log(menupos);
    if (menupos.left + menu.width() > $(window).width()) {
        var newpos = -$(menu).width();
        menu.css({ left: newpos });    
    }
});

/* bootstrap dropdown hover menu*/

body {
  font-family: 'PT Sans', sans-serif;
  font-size: 13px;
  font-weight: 400;
  color: #4f5d6e;
  position: relative;
  background: rgb(26, 49, 95);
  background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, rgba(26, 49, 95, 1)), color-stop(10%, rgba(26, 49, 95, 1)), color-stop(24%, rgba(29, 108, 141, 1)), color-stop(37%, rgba(41, 136, 151, 1)), color-stop(77%, rgba(39, 45, 100, 1)), color-stop(90%, rgba(26, 49, 95, 1)), color-stop(100%, rgba(26, 49, 95, 1)));
  filter: progid: DXImageTransform.Microsoft.gradient( startColorstr='#1a315f', endColorstr='#1a315f', GradientType=0);
}

nav {
  margin-top: 60px;
  box-shadow: 5px 4px 5px #000;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">

<!-- Optional theme -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap-theme.min.css" integrity="sha384-rHyoN1iRsVXV4nD0JutlnGaslCJuC7uwjduW9SVrLvRYooPp2bWYgmgJQIXwl/Sp" crossorigin="anonymous">
<div class="body-wrap">
  <div class="container">
    <nav class="navbar navbar-inverse" role="navigation">
      <div class="container-fluid">
        <div class="navbar-header">
          <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1">
            <span class="sr-only">Toggle navigation</span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
          </button>
          <a class="navbar-brand" href="#">Brand</a>
        </div>

        <!-- Collect the nav links, forms, and other content for toggling -->
        <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
          <ul class="nav navbar-nav">
            <li class="active"><a href="#">Link</a></li>
            <li><a href="#">Link</a></li>
            <li class="dropdown">
              <a href="#" class="dropdown-toggle" data-toggle="dropdown">Dropdown <b class="caret"></b></a>
              <ul class="dropdown-menu">
                <li><a href="#">Action</a></li>
                <li><a href="#">Another action</a></li>
                <li><a href="#">Something else here</a></li>
                <li class="divider"></li>
                <li><a href="#">Separated link</a></li>
                <li class="divider"></li>
                <li><a href="#">One more separated link</a></li>
              </ul>
            </li>
          </ul>

          <ul class="nav navbar-nav navbar-right">
            <li><a href="#">Link</a></li>
            <li class="dropdown">
              <a href="#" class="dropdown-toggle" data-toggle="dropdown">Dropdown <b class="caret"></b></a>
              <ul class="dropdown-menu">
                <li><a href="#">Action</a></li>
                <li><a href="#">Another action</a></li>
                <li><a href="#">Something else here</a></li>
                <li class="divider"></li>
                <li class="dropdown">
              <a href="#" class="dropdown-toggle" data-toggle="dropdown">Dropdown <b class="caret"></b></a>
              <ul class="dropdown-menu">
                <li><a href="#">Action</a></li>
                <li><a href="#">Another action</a></li>
                <li><a href="#">Something else here</a></li>
                <li class="divider"></li>
                <li><a href="#">Separated link</a></li>
              </ul>
            </li>
                <li><a href="#">Separated link</a></li>
              </ul>
            </li>
          </ul>
        </div>
        <!-- /.navbar-collapse -->
      </div>
      <!-- /.container-fluid -->
    </nav>
  </div>
</div>

Answer 1

由于您使用的是Bootstrap，并且在给定的下拉列表中绑定了Bootstrap事件，因此只需在事件执行后立即添加代码即可。

按照文档Bootstrap 3 Dropdown Events中的说明设置条件（您可能需要检查Bootstrap 4事件）

如果您对覆盖Bootstrap感到更舒服，请直接禁用所有已与给定元素绑定的事件，即

$( '.dropdown' ).off( );

或者，使用 show.bs.dropdown ， shown.bs.dropdown ， hide.bs.dropdown ，隐藏。 bs.dropdown 。更确切地说，使用显示和隐藏事件。所以

$( '.dropdown' ).on( 'shown.bs.dropdown, hidden.bs.dropdown', function( ) {  
    var menu = $(this).children('ul');
    var menupos = menu.offset();
    console.log(menupos);
    if (menupos.left + menu.width() > $(window).width()) {
        var newpos = -$(menu).width();
        menu.css({ left: newpos });    
    }
} );

我还没有测试过，但是应该可以给您预期的结果

显示元素时元素偏移返回0，而不是实际值

1 个答案: