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固定高度父级应包括绝对/固定位置子级

position css html

vrintle Jake · 技术社区 · 7 年前

div.settings 作为“家长”和 #mainMenu 作为“孩子”。

现在,我想创建一个类似于Windows中的下拉列表。所以,父母的身高需要 固定的 fixed

* {
  box-sizing: border-box;
  cursor: default;
  user-select: none;
  font-family: Roboto;
  font-weight: 400;
}

.settings {
  padding: 7px 16px;
  border: 0.5px solid #7777;
  border-radius: 4px;
}

#mainMenu {
  position: fixed;
  /* or absolute */
  display: inline-flex;
  flex-flow: column wrap;
  justify-content: flex-start;
  align-items: stretch;
}

span.opt {
  padding: 5px 20px;
  flex-grow: 1;
  margin: 0;
  background: #777;
  color: #FFF;
  text-align: center;
  display: none;
}

span.selected {
  display: inline-block !important;
  background: #28F;
}

#mainMenu:hover>span.opt {
  display: inline-block;
}

<div class='settings'>
  <p>Select default browser</p>
  <span id='mainMenu'>
    <span class='opt'>Google Chrome</span>
    <span class='opt'>Mozilla Firefox</span>
    <span class='opt'>Safari</span>
    <span class='opt selected'>Microsoft Edge</span>
    <span class='opt'>Opera</span>
    <span class='opt'>Internet Explorer</span>
  </span>
</div>

问题

我想让父母包括菜单包含在其内容中。如下图所示:

注意 :只有CSS(因为没有任何东西是动态的而没有效果),并且我在代码中只显示了一个菜单(以最小化复杂性和代码长度)。实际上,可能有 许多的

简言之,我只想让孩子保持固定的位置,在父母身体内部,保持固定的高度。

4 回复 | 直到 5 年前

Arleigh Hix 7 年前

您可以将菜单包装在一个具有最小高度的div中,以便在父div中保留该空间, 使用“占位符”span.opt.selected with visibility:hidden(请参阅更新的代码段)。

* {
  box-sizing: border-box;
  cursor: default;
  user-select: none;
  font-family: Roboto;
  font-weight: 400;
}

.settings {
  padding: 7px 16px;
  border: 0.5px solid #7777;
  border-radius: 4px;
  background-color: inherit;
}

#mainMenu {
  position: fixed;
  /* or absolute */
  display: inline-flex;
  flex-flow: column wrap;
  justify-content: flex-start;
  align-items: stretch;
}

span.opt {
  padding: 5px 12px;
  flex-grow: 1;
  margin: 0;
  background: #777;
  color: #FFF;
  text-align: center;
  display: none;
}

span.placeholder {
  visibility: hidden;
}

span.selected {
  display: inline-block !important;
  background: #28F;
}

#mainMenu:hover>span.opt {
  display: inline-block;
}

<div class='settings'>
  <p>Select default browser</p>
  <span id='mainMenu'>
    <span class='opt'>Google Chrome</span>
    <span class='opt'>Mozilla Firefox</span>
    <span class='opt'>Safari</span>
    <span class='opt selected'>Microsoft Edge</span>
    <span class='opt'>Opera</span>
    <span class='opt'>Internet Explorer</span>
  </span>
  <span class='opt selected placeholder'>placeholder</span>
</div>

evgeni fotia 7 年前

我添加了一个悬停效果,所以你可以看到。设置高度是动态的

var mainMenu = document.getElementById("mainMenu");
var heightc = document.getElementById("heightc");
var opt = document.getElementsByClassName("opt");
var scrollHeight = 0;
mainMenu.addEventListener('mouseenter', function(){
    for(var i=0; i<opt.length; i++){
       if(opt[i].className.indexOf("selected") > 0){
          var dm = i*opt[i].offsetHeight;
          mainMenu.style.bottom = dm + 'px';
          heightc.style.paddingBottom = dm + 'px';
          scrollHeight = window.scrollY;
          window.scrollTo(0, window.scrollY+dm);
       }
    }
});


mainMenu.addEventListener('mouseleave', function(){
    mainMenu.style.bottom = 0;
    heightc.style.paddingBottom = 0;
    window.scrollTo(0, scrollHeight); 
});

* {
	box-sizing: border-box;
	cursor: default;
	user-select: none;
	font-family: Roboto;
	font-weight: 400;
}
#fs{
  height: 1000px;
}
.settings {
	padding: 7px 16px;
	border: 0.5px solid #7777;
	border-radius: 4px;
}
#mainMenu {
	display: inline-flex;
	flex-flow: column wrap;
	justify-content: flex-start;
	align-items: stretch;
  position: relative;
}
/* added */
#mainMenu span{
  display: none;
}
#mainMenu .selected{
  display: block;
}
#mainMenu:hover .opt{
  display: block;
}
/* end added */
span.opt {
	padding: 5px 12px;
	flex-grow: 1;
	margin: 0;
	background: #777;
	color: #FFF;
	text-align: center;
}
span.selected {
	display: inline-block !important;
	background: #28F;
}

<div class='settings'>
  <p id="heightc">Select default browser</p>
  <span id='mainMenu'>
    <span class='opt'>Google Chrome</span>
    <span class='opt'>Mozilla Firefox</span>
    <span class='opt'>Safari</span>
    <span class='opt selected'>Microsoft Edge</span>
    <span class='opt'>Opera</span>
    <span class='opt'>Internet Explorer</span>
  </span>
</div>
<div id="fs"></div>

sol 7 年前

我希望父级在其内容中包含菜单

添加位置 absolute 或 fixed

const MENU = document.getElementById('mainMenu');
const SELECTION = document.getElementById('selection');
const OPTION_CONTAINER = document.getElementById('options');
const OPTIONS = [...document.querySelectorAll('.opt')];

let height;

function addEventListeners() {
  OPTIONS.forEach((option, index) => {
    option.addEventListener('click', (e) => {
      let val = option.innerText;
      SELECTION.innerText = val;
      positionMenu(index);

      if (MENU.classList.contains('is-open')) {
        MENU.classList.remove('is-open')
      }
    })
  })

  MENU.addEventListener('mouseenter', () => {
    MENU.classList.add('is-open');
  })

  MENU.addEventListener('mouseleave', () => {
    MENU.classList.remove('is-open');
  })
}

function getOptionHeight() {
  height = OPTIONS[0].getBoundingClientRect().height;
}

function positionMenu(index) {
  index--;
  OPTION_CONTAINER.style.transform = `translateY(-${index * height}px)`;
}

getOptionHeight();
addEventListeners();

* {
  box-sizing: border-box;
  cursor: default;
  user-select: none;
  font-family: Roboto;
  font-weight: 400;
}

.settings {
  /* demo */
  margin: 100px 0 100px;
  
  padding: 7px 16px;
  border: 0.5px solid #7777;
  border-radius: 4px;
}

.options-container {
  position: relative;
  width: 200px;
}

.options {
  display: inline-flex;
  flex-flow: column wrap;
  justify-content: flex-start;
  align-items: stretch;
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  opacity: 0;
  pointer-events: none;
}

.opt {
  padding: 5px 20px;
  flex-grow: 1;
  margin: 0;
  background: #777;
  color: #FFF;
  text-align: center;
  display: inline-block;
  width: 100%;
}

.selected {
  background: #28F;
}

.options-container.is-open .options {
  opacity: 1;
  pointer-events: auto;
}

.opt:hover {
  background: #28F;
}

<div class='settings'>
  <p>Select default browser</p>
  <div id='mainMenu' class="options-container">
    <span id="selection" class="opt selected">Select</span>
    <div class="options" id="options">
      <span class='opt'>Google Chrome</span>
      <span class='opt'>Mozilla Firefox</span>
      <span class='opt'>Safari</span>
      <span class='opt'>Microsoft Edge</span>
      <span class='opt'>Opera</span>
      <span class='opt'>Internet Explorer</span>
    </div>
  </div>
</div>

Mattia Pontonio 7 年前

JavaScript和CSS解决方案建议

为了 控制定位 最好将选项和选中的选项保持在两个位置 不同的背景 然后再做手术 top属性 以编程方式 . 在那之后,你必须解决问题价值呢得到和设置在标记中。

function setTop() {
  let height = document.querySelector(".opt").clientHeight;
  document.querySelector(".options").style.top = height * 3 * (-1) + "px";
}
setTop();

* {
      box-sizing: border-box;
      cursor: default;
      user-select: none;
      font-family: Roboto;
      font-weight: 400;
    }

    .settings {
      padding: 7px 16px;
      border: 0.5px solid #7777;
      border-radius: 4px;
    }

    #mainMenu {
      position: relative;
      display: block;
      width:300px;
    }
    #mainMenu .options {
      position: absolute;
      display: none;
      width:100%;
    }
    #mainMenu:hover .options {
      display: block;
    }

    #mainMenu .opt {
      padding: 5px 20px;
      background: #777;
      color: #FFF;
      text-align: center;
    }
    #mainMenu .opt.selected {
      background: #28F;
    }
    #mainMenu .selection {
      display:block;
    }

<div class='settings'>
      <p>Select default browser</p>
      <div id='mainMenu'>
        <span class='opt selected selection'>Microsoft Edge</span>
        <div class='options' style="top:0;">
          <div class='opt'>Google Chrome</div>
          <div class='opt'>Mozilla Firefox</div>
          <div class='opt'>Safari</div>
          <div class='opt selected'>Microsoft Edge</div>
          <div class='opt'>Opera</div>
          <div class='opt'>Internet Explorer</div>
        </div>
      </div>
    </div>