javascript - 我怎样才能正确使用 jQuery 来修复这个 fencepost 案例？

Question

我有一个函数

function giveTheseEqualHeight ( selector )
{
     // selector: CSS selector of elements on the page to be forced to have the same height

     var these = $(selector);
     if (these.length < 2) return; 
     these.height('auto');
     var maxHeight = these.first().height();
     these.each(function(){
        var thisHeight = $(this).height();
        if (thisHeight > maxHeight) maxHeight = thisHeight;                
     });
     these.height(maxHeight);
}

这是非常不言自明的。

示例用例:

giveTheseEqualHeight('.service-column h3'); 

将使属于 service-column 类元素的后代的所有 h3 元素具有相同的高度，方法是增加比最高高度小的元素。

问题是循环

             these.each(function(){
                var thisHeight = $(this).height();
                if (thisHeight > maxHeight) maxHeight = thisHeight;                
             });

不需要在第一次迭代时执行它的主体——这相当于无用的操作。我想从第二项开始，而不是 these.each。这可能吗？

Answer 1

如果获取高度数组然后使用原生 Math.max 取最大值，则可以避免计算第一个元素的高度:

function giveTheseEqualHeight(selector) {
    var these = $(selector);
    if (these.length < 2) return;
    these.height('auto');

    var maxHeight = Math.max.apply(null, these.map(function(el) {
        return $(this).height();
    }));
    these.height(maxHeight);
}

这是一个演示:

function giveTheseEqualHeight(selector) {
    var these = $(selector);
    if (these.length < 2) return;
    these.height('auto');
    
    var maxHeight = Math.max.apply(null, these.map(function(el) {
    	return $(this).height();
    }));
    these.height(maxHeight);
}

giveTheseEqualHeight('div')

div {display: inline-block;background: #EEE; vertical-align: top;}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<div>Lorem</div>
<div>Test <br>rest</div>
<div>Test <br> and rest <br>on the <br>west</div>