简单DOM类选择器

Question

<ul> 
    <li> <div class="time"> at 2011-02-05 17:44:28</div></li> 
    <li> <div class="time"> at 2011-02-05 17:40:20</div></li> 
    <li> <div class="time"> at 2011-02-05 17:15:11</div></li> 
    <li> <div class="time"> at 2011-02-05 17:04:14</div></li> 
    <li> <div class="time"> at 2011-02-05 15:54:56</div></li> 
</ul> 

//Reformat timeStamps 
var timeIndex = 0; 
while (timeIndex < 51) 
{ 
    var timeIndexHTML = document.getElementsByClassName("time")[timeIndex].innerHTML; 
    timeIndexHTML = "Reformatted time"; 
    document.getElementsByClassName("time")[timeIndex].innerHTML = timeIndexHTML; 
    timeIndex++; 
} 

如何检测类的最后一个元素，然后使51变量？

// 
//*****************************EDITS HERE************************************** 
// 
//Example: 
    var LAST_ELEMENT_OF_CLASS = someMagicCode("time"); 

然后

while (timeIndex < LAST_ELEMENT_OF_CLASS +1){...} 

注意它目前并没有因为它试图评估

document.getElementsByClassName("time")[5] 

不存在

Answer 1

让我猜的工作。你想要的是这样的：

var elems = document.getElementsByClassName("time"); 
for(var timeIndex = 0; timeIndex < elems.length; ++timeIndex) 
{ 
    elems[timeIndex].innerHTML = "Reformatted time"; 
} 

（如果这不是你想要的，请澄清的问题）