它可以只用CSS，不需要javascript

运行演示

[data-tooltip]:before { /* needed - do not touch */ content: attr(data-tooltip); position: absolute; opacity: 0; /* customizable */ transition: all 0.15s ease; padding: 10px; color: #333; border-radius: 10px; box-shadow: 2px 2px 1px silver; } [data-tooltip]:hover:before { /* needed - do not touch */ opacity: 1; /* customizable */ background: yellow; margin-top: -50px; margin-left: 20px; } [data-tooltip]:not([data-tooltip-persistent]):before { pointer-events: none; } /* FOR TEST PURPOSES ONLY */ div { border: 1px solid silver; background: #ddd; margin: 20px; padding: 10px; } <div>Standard div, no tooltip here</div> <div data-tooltip="Hi, I'm a tooltip. Pretty easy uh ? ;)">Div with standard tooltip. Hover me to see the tooltip. <br/>Hovering the tooltip doesn't matter: <br/>if you hover out of my boundaries, the tooltip will disappear.</div> <div data-tooltip="Hi, I'm a persistent tooltip. I won't disappear when hovering me even if out of my parent boundaries. I'll also prevent other tooltips to fire :)" data-tooltip-persistent="foo">Div with persistent tooltip. Hover me to see the tooltip. <br/>The tooltip won't expire until you hover on me OR it.</div>

Apply a custom HTML attribute, eg. data-tooltip="bla bla" to your object (div or whatever): <div data-tooltip="bla bla"> something here </div> Define the :before pseudoelement of each [data-tooltip] object to be transparent, absolutely positioned and with data-tooltip="" value as content: [data-tooltip]:before { position : absolute; content : attr(data-tooltip); opacity : 0; } Define :hover:before hovering state of each [data-tooltip] to make it visible: [data-tooltip]:hover:before { opacity : 1; } Apply your styles (color, size, position etc) to the tooltip object; end of the story.

在演示中，我定义了另一个规则来指定当鼠标悬停在工具提示上但不在父工具提示上时，工具提示是否必须消失，使用另一个自定义属性data-tooltip-persistent和一个简单的规则:

[data-tooltip]:not([data-tooltip-persistent]):before {
    pointer-events: none;
}

注1:浏览器的覆盖范围很广，但可以考虑为旧的IE使用javascript回退(如果需要的话)。

注2:一种增强可能是添加一些javascript来计算鼠标位置，并通过改变应用于它的类将其添加到伪元素中。

下面是一个简单的工具提示实现，它可以考虑鼠标的位置以及窗口的高度和宽度:

function showTooltip(e) { var tooltip = e.target.classList.contains("tooltip") ? e.target : e.target.querySelector(":scope .tooltip"); tooltip.style.left = (e.pageX + tooltip.clientWidth + 10 < document.body.clientWidth) ? (e.pageX + 10 + "px") : (document.body.clientWidth + 5 - tooltip.clientWidth + "px"); tooltip.style.top = (e.pageY + tooltip.clientHeight + 10 < document.body.clientHeight) ? (e.pageY + 10 + "px") : (document.body.clientHeight + 5 - tooltip.clientHeight + "px"); } var tooltips = document.querySelectorAll('.couponcode'); for(var i = 0; i < tooltips.length; i++) { tooltips[i].addEventListener('mousemove', showTooltip); } .couponcode { color: red; cursor: pointer; } .couponcode:hover .tooltip { display: block; } .tooltip { position: absolute; white-space: nowrap; display: none; background: #ffffcc; border: 1px solid black; padding: 5px; z-index: 1000; color: black; } Lorem ipsum dolor sit amet, <span class="couponcode">consectetur adipiscing<span class="tooltip">This is a tooltip</span></span> elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in <span class="couponcode">reprehenderit<span class="tooltip">This is another tooltip</span></span> in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est <span class="couponcode">laborum<span class="tooltip">This is yet another tooltip</span></span>.

(也可以参看这把小提琴)

工具提示定位纯css

div { position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); -ms-transform: translate(-50%, -50%); /* IE 9 */ -webkit-transform: translate(-50%, -50%); /* Chrome, Safari, Opera */ text-align: center; } .tooltip { position: relative; display: inline-block; border-bottom: 1px dotted black; } .tooltip .tooltiptext { visibility: hidden; width: 120px; background-color: black; color: #fff; //text-align: center; border-radius: 6px; padding: 5px 0; /* Position the tooltip */ position: absolute; z-index: 1; } .tooltip:hover .tooltiptext { visibility: visible; } .toolLeft { top: -5px; right: 105%; } .toolRight { top: -5px; left: 105%; } .toolTop { bottom: 100%; left: 50%; margin-left: -60px; } .toolBottom { top: 100%; left: 50%; margin-left: -60px; } <div> <div class="tooltip">Top <span class="tooltiptext toolTop">Tooltip text</span></div><br /> <div class="tooltip">Left <span class="tooltiptext toolLeft">Tooltip text</span></div><br /> <div class="tooltip">Right <span class="tooltiptext toolRight">Tooltip text</span></div><br /> <div class="tooltip">Bottom <span class="tooltiptext toolBottom">Tooltip text</span></div><br /> </div>

对于基本的工具提示，您需要:

<div title="This is my tooltip">

如:

.visible { 高度:3他们; 宽度:10 em; 背景:黄色; } <div title="This is my tooltip" class="visible"></div> .

对于一个更花哨的javascript版本，你可以查看:

https://jqueryhouse.com/best-jquery-tooltip-plugins/

上面的链接提供了25个工具提示选项。

你也可以使用这个作为工具提示…它的工作原理是一样的，但你必须写额外的标签。

<abbr title="THis is tooltip"></abbr>

我的版本是

.tooltip{
display: inline;
position: relative; /** very important set to relative*/
}

.tooltip:hover:after{
background: #333;
background: rgba(0,0,0,.8);
border-radius: 5px;
bottom: 26px;
color: #fff;
content: attr(title); /**extract the content from the title */
left: 20%;
padding: 5px 15px;
position: absolute;
z-index: 98;
width: 220px;
}

.tooltip:hover:before{
border: solid;
border-color: #333 transparent;
border-width: 6px 6px 0 6px;
bottom: 20px;
content: "";
left: 50%;
position: absolute;
z-index: 99;
}

然后是HTML

<div title="This is some information for our tooltip." class="tooltip">bar </div>