ZH奶酪：HTML元素文本溢出显示省略号(...)

一 单行文本

overflow: hidden;
text-overflow: ellipsis;
white-space: nowrap;

overflow 属性规定当内容溢出元素框时发生的事情。

visible	默认值。内容不会被修剪，会呈现在元素框之外。
hidden	内容会被修剪，并且其余内容是不可见的。
scroll	内容会被修剪，但是浏览器会显示滚动条以便查看其余的内容。
auto	如果内容被修剪，则浏览器会显示滚动条以便查看其余的内容。
inherit	规定应该从父元素继承 overflow 属性的值。

　　

text-overflow 属性规定当文本溢出包含元素时发生的事情。

clip：修剪文本；

ellipsis：显示省略号来代表被修剪的文本；

string：使用给定的字符串来代表被修剪的文本；

white-space 属性设置如何处理元素内的空白。

normal	默认。空白会被浏览器忽略。
pre	空白会被浏览器保留。其行为方式类似 HTML 中的 <pre> 标签。
nowrap	文本不会换行，文本会在在同一行上继续，直到遇到 <br> 标签为止。
pre-wrap	保留空白符序列，但是正常地进行换行。
pre-line	合并空白符序列，但是保留换行符。
inherit	规定应该从父元素继承 white-space 属性的值。

二 多行文本，提供了几种方法，效果图中的每一段文字对应一个方法：

HTML代码

<h1>Line Clampin'</h1>

<h2>Weird WebKit Flexbox Way</h2>
<div class="module line-clamp">
  <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>
</div>

<h2>Fade Out Way</h2>
<div class="module fade">
  <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>
</div>

<h2>Opera Overflow Way</h2>
<div class="module last-line">
  <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>
</div>

<h2>Clamp.js Way</h2>
<div class="module js">
  <p id="clampjs">Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>
</div>

<h2>ftellipsis Way</h2>
<div class="module js ftellipsis" id="ftellipsis">
  <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>
</div>

<h2>TextOverflowClamp.js Way</h2>
<div class="module js textoverflowclamp" id="textoverflowclamp">
  <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>
</div>

CSS代码

@import url(http://fonts.googleapis.com/css?family=Open+Sans);

body {
  padding: 20px;
  font: 1.2em/1.2em 'Open Sans', sans-serif;
}
.module {
  width: 250px;
  margin: 0 0 1em 0;
  overflow: hidden;
}
.module p {
  margin:;
}

.line-clamp {
  display: -webkit-box;
  -webkit-line-clamp:;
  -webkit-box-orient: vertical;
}

.fade {
  position: relative;
  height: 3.6em; /* exactly three lines */
}
.fade:after {
  content: "";
  text-align: right;
  position: absolute;
  bottom:;
  right:;
  width: 70%;
  height: 1.2em;
  background: linear-gradient(to right, rgba(255, 255, 255, 0), rgba(255, 255, 255, 1) 50%);
}

.last-line {
  height: 3.6em; /* exactly three lines */
  text-overflow: -o-ellipsis-lastline;
}

.ftellipsis {
  height: 3.6em;
}

h1 {
  margin: 0 0 1em 0;
}
h2 {
  font-size: 1.2em;
}

JS代码

// https://github.com/josephschmitt/Clamp.js
var module = document.getElementById("clampjs");
$clamp(module, {clamp: 2});

// https://github.com/ftlabs/ftellipsis
var element = document.getElementById('ftellipsis');
var ellipsis = new Ellipsis(element);

ellipsis.calc();
ellipsis.set();

// http://codepen.io/Merri/pen/Dsuim
/**
  * TextOverflowClamp.js
  *
  * Updated 2013-05-09 to remove jQuery dependancy.
  * But be careful with webfonts!
  */

// bind function support for older browsers without it
// https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Function/bind
if (!Function.prototype.bind) {
  Function.prototype.bind = function (oThis) {
    if (typeof this !== "function") {
      // closest thing possible to the ECMAScript 5 internal IsCallable function
      throw new TypeError("Function.prototype.bind - what is trying to be bound is not callable");
    }

    var aArgs = Array.prototype.slice.call(arguments, 1),
        fToBind = this,
        fNOP = function () {},
        fBound = function () {
          return fToBind.apply(this instanceof fNOP && oThis
                                 ? this
                                 : oThis,
                               aArgs.concat(Array.prototype.slice.call(arguments)));
        };

    fNOP.prototype = this.prototype;
    fBound.prototype = new fNOP();

    return fBound;
  };
}

// the actual meat is here
(function(w, d){
    var clamp, measure, text, lineWidth,
        lineStart, lineCount, wordStart,
        line, lineText, wasNewLine,
    ce = d.createElement.bind(d),
    ctn = d.createTextNode.bind(d);

    // measurement element is made a child of the clamped element to get it's style
    measure = ce('span');

    (function(s){
        s.position = 'absolute'; // prevent page reflow
        s.whiteSpace = 'pre'; // cross-browser width results
        s.visibility = 'hidden'; // prevent drawing
    })(measure.style);

    clamp = function (el, lineClamp) {
    // make sure the element belongs to the document
    if(!el.ownerDocument || !el.ownerDocument === d) return;
        // reset to safe starting values
        lineStart = wordStart = 0;
        lineCount = 1;
        wasNewLine = false;
        lineWidth = el.clientWidth;
        // get all the text, remove any line changes
        text = (el.textContent || el.innerText).replace(/\n/g, ' ');
        // remove all content
        while(el.firstChild !== null)
            el.removeChild(el.firstChild);
        // add measurement element within so it inherits styles
        el.appendChild(measure);
        // http://ejohn.org/blog/search-and-dont-replace/
        text.replace(/ /g, function(m, pos) {
            // ignore any further processing if we have total lines
      if(lineCount === lineClamp) return;
            // create a text node and place it in the measurement element
            measure.appendChild(ctn(text.substr(lineStart, pos - lineStart)));
            // have we exceeded allowed line width?
            if(lineWidth < measure.clientWidth) {
                if(wasNewLine) {
                    // we have a long word so it gets a line of it's own
                    lineText = text.substr(lineStart, pos + 1 - lineStart);
                    // next line start position
                    lineStart = pos + 1;
                } else {
                    // grab the text until this word
                    lineText = text.substr(lineStart, wordStart - lineStart);
                    // next line start position
                    lineStart = wordStart;
                }
                // create a line element
                line = ce('span');
                // add text to the line element
                line.appendChild(ctn(lineText));
                // add the line element to the container
                el.appendChild(line);
                // yes, we created a new line
                wasNewLine = true;
        lineCount++;
            } else {
                // did not create a new line
                wasNewLine = false;
            }
            // remember last word start position
            wordStart = pos + 1;
            // clear measurement element
            measure.removeChild(measure.firstChild);
        });
        // remove the measurement element from the container
        el.removeChild(measure);
        // create the last line element
        line = ce('span');
        // give styles required for text-overflow to kick in
        (function(s){
            s.display = 'inline-block';
            s.overflow = 'hidden';
            s.textOverflow = 'ellipsis';
            s.whiteSpace = 'nowrap';
            s.width = '100%';
        })(line.style);
        // add all remaining text to the line element
        line.appendChild(ctn(text.substr(lineStart)));
        // add the line element to the container
        el.appendChild(line);
    }
    w.clamp = clamp;
})(window, document);

// the only bit of jQuery
$(window).bind('load', function() {
  clamp(document.getElementById('textoverflowclamp'), 3);
});

其中

（1）-webkit-line-clamp 这种方法指支持部分浏览器，而且要与其他两个属性同时使用：

.line-clamp {
display: -webkit-box;
-webkit-line-clamp: 3;
-webkit-box-orient: vertical;
}

（2）clamp.js 下载地址及使用方法：https://github.com/josephschmitt/Clamp.js

（3）ftellipsis 下载地址及使用方法：https://github.com/ftlabs/ftellipsis

（4）jQuery.dotdotdot 下载地址及使用方法：https://github.com/BeSite/jQuery.dotdotdot

参考文章：

[1] https://css-tricks.com/line-clampin/

[2] http://www.css88.com/archives/5206

[3] http://codepen.io/Merri/pen/Dsuim

[4] http://codepen.io/feiwen8772/pen/AckqK