你不需要jQuery来做这个…

function sortUnorderedList(ul, sortDescending) {
  if(typeof ul == "string")
    ul = document.getElementById(ul);

  // Idiot-proof, remove if you want
  if(!ul) {
    alert("The UL object is null!");
    return;
  }

  // Get the list items and setup an array for sorting
  var lis = ul.getElementsByTagName("LI");
  var vals = [];

  // Populate the array
  for(var i = 0, l = lis.length; i < l; i++)
    vals.push(lis[i].innerHTML);

  // Sort it
  vals.sort();

  // Sometimes you gotta DESC
  if(sortDescending)
    vals.reverse();

  // Change the list on the page
  for(var i = 0, l = lis.length; i < l; i++)
    lis[i].innerHTML = vals[i];
}

易于使用…

sortUnorderedList("ID_OF_LIST");

现场演示→

$(".list li").sort(asc_sort).appendTo('.list');
//$("#debug").text("Output:");
// accending sort
function asc_sort(a, b){
    return ($(b).text()) < ($(a).text()) ? 1 : -1;    
}

// decending sort
function dec_sort(a, b){
    return ($(b).text()) > ($(a).text()) ? 1 : -1;    
}

现场演示:http://jsbin.com/eculis/876/edit

为了使这个工作在包括Chrome在内的所有浏览器中工作，你需要使sort()的回调函数返回-1、0或1。

参见http://inderpreetsingh.com/2010/12/01/chromes-javascript-sort-array-function-is-different-yet-proper/

function sortUL(selector) {
    $(selector).children("li").sort(function(a, b) {
        var upA = $(a).text().toUpperCase();
        var upB = $(b).text().toUpperCase();
        return (upA < upB) ? -1 : (upA > upB) ? 1 : 0;
    }).appendTo(selector);
}
sortUL("ul.mylist");

HTML

<ul id="list">
    <li>alpha</li>
    <li>gamma</li>
    <li>beta</li>
</ul>

JavaScript

function sort(ul) {
    var ul = document.getElementById(ul)
    var liArr = ul.children
    var arr = new Array()
    for (var i = 0; i < liArr.length; i++) {
        arr.push(liArr[i].textContent)
    }
    arr.sort()
    arr.forEach(function(content, index) {
        liArr[index].textContent = content
    })
}

sort("list")

j挑战者演示https://j挑战者le.net970061nw/

在这里，我们将ul中li元素的所有值推入特定的id(我们作为函数参数提供)到数组arr中，并使用sort()方法对其排序，该方法默认按字母顺序排序。数组arr排序后，我们使用forEach()方法循环该数组，并将所有li元素的文本内容替换为排序内容

你不需要jQuery来做这个…

function sortUnorderedList(ul, sortDescending) {
  if(typeof ul == "string")
    ul = document.getElementById(ul);

  // Idiot-proof, remove if you want
  if(!ul) {
    alert("The UL object is null!");
    return;
  }

  // Get the list items and setup an array for sorting
  var lis = ul.getElementsByTagName("LI");
  var vals = [];

  // Populate the array
  for(var i = 0, l = lis.length; i < l; i++)
    vals.push(lis[i].innerHTML);

  // Sort it
  vals.sort();

  // Sometimes you gotta DESC
  if(sortDescending)
    vals.reverse();

  // Change the list on the page
  for(var i = 0, l = lis.length; i < l; i++)
    lis[i].innerHTML = vals[i];
}

易于使用…

sortUnorderedList("ID_OF_LIST");

现场演示→

改进基于Jeetendra Chauhan的回答

$('ul.menu').each(function(){
    $(this).children('li').sort((a,b)=>a.innerText.localeCompare(b.innerText)).appendTo(this);
});

为什么我认为这是一个进步:

using each to support running on more than one ul using children('li') instead of ('ul li') is important because we only want to process direct children and not descendants using the arrow function (a,b)=> just looks better (IE not supported) using vanilla innerText instead of $(a).text() for speed improvement using vanilla localeCompare improves speed in case of equal elements (rare in real life usage) using appendTo(this) instead of using another selector will make sure that even if the selector catches more than one ul still nothing breaks