在无序列表中的项之后添加管道分隔符，除非该项是一行中的最后一个项

Use :after pseudo selector. Look http://jsfiddle.net/A52T8/1/

<ul>
<li>Dogs</li>
<li>Cats</li>
<li>Lions</li>
<li>Tigers</li>
<li>Zebras</li>
<li>Giraffes</li>
<li>Bears</li>
<li>Hippopotamuses</li>
<li>Antelopes</li>
<li>Unicorns</li>
<li>Seagulls</li>
</ul>


ul li { float: left; }
ul li:after { content: "|"; padding: 0 .5em; }

EDIT:

jQuery solution:

html:

<div>
<ul id="animals">
<li>Dogs</li>
<li>Cats</li>
<li>Lions</li>
<li>Tigers</li>
<li>Zebras</li>
<li>Giraffes</li>
<li>Bears</li>
<li>Hippopotamuses</li>
<li>Antelopes</li>
<li>Unicorns</li>
<li>Seagulls</li>
<li>Monkey</li>
<li>Hedgehog</li>
<li>Chicken</li>
<li>Rabbit</li>
<li>Gorilla</li>
</ul>
</div>

css:

div { width: 300px; }
ul li { float: left; border-right: 1px solid black; padding: 0 .5em; }
ul li:last-child { border: 0; }

jQuery

var maxWidth = 300, // Your div max-width
totalWidth = 0;
$('#animals li').each(function(){
var currentWidth = $(this).outerWidth(),
nextWidth = $(this).next().outerWidth();
totalWidth += currentWidth;
if ( (totalWidth + nextWidth) > maxWidth ) {
$(this).css('border', 'none');
totalWidth = 0;
}
});

Take a look here. I also added a few more animals. http://jsfiddle.net/A52T8/10/

Yes, you'll need to use pseudo elements AND pseudo selectors: http://jsfiddle.net/cYky9/

One solution is to style the left border like so:

li { display: inline; }
li + li {
border-left: 1px solid;
margin-left:.5em;
padding-left:.5em;
}

However, this may not give you desirable results if the entire lists wraps, like it does in your example. I.e. it would give something like:

foo | bar | baz
| bob | bill
| judy

在展示代码之前，值得一提的是，IE8支持:first-child，但不支持:last-child，因此在类似的情况下，您应该使用:first-child伪类。

Demo

#menu{
list-style: none;
}
#menu li{
display: inline;
padding: 0 10px;
border-left: solid 1px black;
}
#menu li:first-child{
border-left: none;
}

<ul id="menu">
<li>Dogs</li>
<li>Cats</li>
<li>Lions</li>
<li>More animals</li>
</ul>

Just

li + li::before {
content: " | ";
}

Of course, this does not actually solve the OP's problem. He wants to elide the vertical bars at the beginning and end of lines depending on where they are broken. I will go out on a limb and assert that this problem is not solvable using CSS, and not even with JS unless one wants to essentially rewrite the browser engine's text-measurement/layout/line breaking logic.

The only pieces of CSS, as far as I can see, that "know" about line breaking are, first, the ::first-line pseudo element, which does not help us here--in any case, it is limited to a few presentational attributes, and does not work together with things like ::before and ::after. The only other aspect of CSS I can think of that to some extent exposes line-breaking is hyphenation. However, hyphenating is all about adding a character (usually a dash) to the end of lines in certain situations, whereas here we are concerned about removing a character (the vertical line), so I just can't see how to apply any kind of hyphenation-related logic, even with the help of properties such as hyphenate-character.

We have the word-spacing property, which is applied intra-line but not at line beginnings and endings, which seems promising, but it defines the width of the space between words, not the character(s) to be used.

One wonders if there's some way to use the text-overflow property, which has the little-known ability to take two values for display of overflow text at both left and right, as in

text-overflow: '' '';

but there still doesn't seem to be any obvious way to get from A to B here.

You can use the following CSS to solve.

ul li { float: left; }
ul li:before { content: "|"; padding: 0 .5em; }
ul li:first-child:before { content: ""; padding: 0; }

Should work on IE8+ as well.

I know I'm a bit late to the party, but if you can put up with having the lines left-justified, one hack is to put the pipes before the items and then put a mask over the left edge, basically like so:

li::before {
content: " | ";
white-space: nowrap;
}


ul, li {
display: inline;
}


.mask {
width:4px;
position: absolute;
top:8px; //position as needed
}

more complete example: http://jsbin.com/hoyaduxi/1/edit

This is possible with flex-box

The keys to this technique:

• A container element set to overflow: hidden.
• Set justify-content: space-between on the ul (which is a flex-box) to force its flex-items to stretch to the left and right edges.
• Set margin-left: -1px on the ul to cause its left edge to overflow the container.
• Set border-left: 1px on the li flex-items.

The container acts as a mask hiding the borders of any flex-items touching its left edge.

.flex-list {
position: relative;
margin: 1em;
overflow: hidden;
}
.flex-list ul {
display: flex;
flex-direction: row;
flex-wrap: wrap;
justify-content: space-between;
margin-left: -1px;
}
.flex-list li {
flex-grow: 1;
flex-basis: auto;
margin: .25em 0;
padding: 0 1em;
text-align: center;
border-left: 1px solid #ccc;
background-color: #fff;
}

<link href="https://cdnjs.cloudflare.com/ajax/libs/meyer-reset/2.0/reset.min.css" rel="stylesheet"/>
<div class="flex-list">
<ul>
<li>Dogs</li>
<li>Cats</li>
<li>Lions</li>
<li>Tigers</li>
<li>Zebras</li>
<li>Giraffes</li>
<li>Bears</li>
<li>Hippopotamuses</li>
<li>Antelopes</li>
<li>Unicorns</li>
<li>Seagulls</li>
</ul>
</div>

I came across a solution today that does not appear to be here already and which seems to work quite well so far. The accepted answer does not work as-is on IE10 but this one does. http://codepen.io/vithun/pen/yDsjf/ credit to the author of course!

.pipe-separated-list-container {
overflow-x: hidden;
}
.pipe-separated-list-container ul {
list-style-type: none;
position: relative;
left: -1px;
padding: 0;
}
.pipe-separated-list-container ul li {
display: inline-block;
line-height: 1;
padding: 0 1em;
margin-bottom: 1em;
border-left: 1px solid;
}

<div class="pipe-separated-list-container">
<ul>
<li>One</li>
<li>Two</li>
<li>Three</li>
<li>Four</li>
<li>Five</li>
<li>Six</li>
<li>Seven</li>
<li>Eight</li>
<li>Nine</li>
<li>Ten</li>
<li>Eleven</li>
<li>Twelve</li>
<li>Thirteen</li>
<li>Fourteen</li>
<li>Fifteen</li>
<li>Sixteen</li>
<li>Seventeen</li>
<li>Eighteen</li>
<li>Nineteen</li>
<li>Twenty</li>
<li>Twenty One</li>
<li>Twenty Two</li>
<li>Twenty Three</li>
<li>Twenty Four</li>
<li>Twenty Five</li>
<li>Twenty Six</li>
<li>Twenty Seven</li>
<li>Twenty Eight</li>
<li>Twenty Nine</li>
<li>Thirty</li>
</ul>
</div>

Slightly modified SCSS version which gives you control of the pipe | size and will eliminate padding from first and last list items while respects borders.

$pipe-list-height: 20px;
$pipe-list-padding: 15px;


.pipe-list {
position: relative;
overflow: hidden;
height: $pipe-list-height;


> ul {
display: flex;
flex-direction: row;


> li {
position: relative;
padding: 0 $pipe-list-padding;


&:after {
content: " ";
position: absolute;
border-right: 1px solid gray;
top: 10%;
right: 0;
height: 75%;
margin-top: auto;
margin-bottom: auto;
}


&:first-child {
padding-left: 0;
}


&:last-child {
padding-right: 0;


&:after {
border-right: none;
}
}
}
}
}

<div class="pipe-list">
<ul>
<li>Link</li>
<li>Link</li>
<li>Link</li>
</ul>
</div>

This should solve the problem without using borders.

li {
display: inline-block !important;
list-style: none;
margin: 0 auto;
height: 14px;
}
ul li::after {
content: " | ";
margin: 0 10px;
}
ul li:last-child:after {
content: '';
margin: 0 10px;
}

<div>
<ul>
<li>One</li>
<li>Two</li>
<li>Three</li>
<li>Four</li>
<li>Five</li>
<li>Six</li>
<li>Seven</li>
<li>Eight</li>
<li>Nine</li>
<li>Ten</li>
<li>Eleven</li>
<li>Twelve</li>
<li>Thirteen</li>
<li>Fourteen</li>
<li>Fifteen</li>
<li>Sixteen</li>
<li>Seventeen</li>
<li>Eighteen</li>
<li>Nineteen</li>
<li>Twenty</li>
<li>Twenty One</li>
<li>Twenty Two</li>
<li>Twenty Three</li>
<li>Twenty Four</li>
<li>Twenty Five</li>
<li>Twenty Six</li>
<li>Twenty Seven</li>
<li>Twenty Eight</li>
<li>Twenty Nine</li>
<li>Thirty</li>
</ul>
</div>