blocks|key|853805|text|并不是所有的事情都必须使用jQuery来完成。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|853806|在普通的旧式javascript中，你可以这样做：|853807|var+pg_url+=+array_fragment[array_fragment.length+-+2]|code-block|syntax|javascript|853808|更简单、更快速:)|853809|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Not everything has to be done using jQuery. 

In plain old javascript you can do:

<pre><code>var pg_url = array_fragment[array_fragment.length - 2]
</code></pre>

Easier and faster :)

blocks|key|853935|text|看起来你也可以使用Javascript的slice方法：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|853936|var+path+=+'a/b/c/d';
path.split('/').slice(-2,+-1)[0];+//+c|code-block|syntax|javascript|853937|你也可以把“数组中倒数第二个元素”看作是“倒数组的第二个元素”：|853938|var+path+=+'a/b/c/d';
path.split('/').reverse()[1];+//+c|853939|entityMap^0|K|5|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|P|$]]

Looks like you can also use Javascript's <code>slice</code> method:

<pre><code>var path = 'a/b/c/d';
path.split('/').slice(-2, -1)[0]; // c
</code></pre>

You can also think of "second to last element in the array" as "second element of the array reversed":

<pre><code>var path = 'a/b/c/d';
path.split('/').reverse()[1]; // c
</code></pre>

blocks|key|854158|text|arr.at(-2);将精确地执行此操作-它返回数组中的最后一秒项。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|854159|854160|const+arr+=+[1,2,3,4];
arr.at(-2);+//+Returns+3|code-block|syntax|javascript|854161|at()方法接受一个正整数或负整数，并返回该索引处的项。负整数从数组中的最后一项开始倒计数。|854162|文档：Array/at|854163|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/at^0|0|B|0|0|0|0|4|0|3|8|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|10|8|@]|D|@]|E|$]]|$1|G|3|H|5|I|7|11|8|@]|D|@]|E|$J|K]]|$1|L|3|M|5|6|7|12|8|@$9|13|A|14|B|C]]|D|@]|E|$]]|$1|N|3|O|5|6|7|15|8|@]|D|@$9|16|A|17|1|18]]|E|$]]|$1|P|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|Q|$R|$5|S|T|U|E|$V|W]]]]

<code>arr.at(-2);</code> will do exaclty that - it returns last second item in an array.
<hr />
<pre><code>const arr = [1,2,3,4];
arr.at(-2); // Returns 3
</code></pre>
The <code>at()</code> method takes a positive or negative integer and returns the item at that index. Negative integers count back from the last item in the array.
Docs: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/at" rel="noreferrer">Array/at</a>

blocks|key|854084|text|这可以通过lodash+_.nth来实现|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|854085|​|854086|var+fragment+=+'/news/article-1/'
var+array_fragment+=+_.split(fragment,+'/');
var+second_last+=+_.nth(array_fragment,+-2);
console.log(second_last);|code-block|syntax|javascript|854087|<script+src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"></script>|854088|854089|entityMap|0|LINK|mutability|MUTABLE|url|https://lodash.com/docs/4.17.11#nth^0|C|5|C|5|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@$9|10|A|11|1|12]]|E|$]]|$1|F|3|G|5|6|7|13|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|14|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|J|7|15|8|@]|D|@]|E|$K|L]]|$1|O|3|G|5|6|7|16|8|@]|D|@]|E|$]]|$1|P|3|-4|5|6|7|17|8|@]|D|@]|E|$]]]|Q|$R|$5|S|T|U|E|$V|W]]]]

This can be covered by lodash <a href="https://lodash.com/docs/4.17.11#nth" rel="noreferrer"><code>_.nth</code></a>:

<div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>var fragment = '/news/article-1/'
var array_fragment = _.split(fragment, '/');
var second_last = _.nth(array_fragment, -2);
console.log(second_last);</code></pre>
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"&gt;&lt;/script&gt;</code></pre>
</div>
</div>

blocks|key|853893|text|var+pg_url+=+array_fragment[array_fragment.length+-2]|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|853894|array_fragment不是一个jquery变量，它是一个普通的旧式javascript变量，所以不需要$()|unstyled|853895|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>var pg_url = array_fragment[array_fragment.length -2]
</code></pre>

array_fragment isn't a jquery variable, it's a plain old javascript variable so no need for $()

blocks|key|637548|text|这个问题很古老，但仍然是相关的。长度为-1的切片是最好的选择，但也可以使用下划线/下划线：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|637549|_.initial()获取除最后一个之外的所有|637550|_.last()获取最后一个|637551|所以你可以这样做|637552|_.last(_.initial([1,2,3,4]))+|code-block|syntax|javascript|637553|或者链式的：|637554|_.chain([1,2,3,4])
+.initial()
+.last()
+.value();|637555|这给你带来了3分。|637556|或在原质询中：|637557|var+fragment+=+'/news/article-1/'
var+array_fragment+=+fragment.split('/');
var+pg_url+=+_.chain(array_fragment).initial().last().value();|637558|entityMap^0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|10|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|11|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|12|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|13|8|@]|9|@]|A|$]]|$1|O|3|P|5|J|7|14|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|15|8|@]|9|@]|A|$]]|$1|S|3|T|5|6|7|16|8|@]|9|@]|A|$]]|$1|U|3|V|5|J|7|17|8|@]|9|@]|A|$K|L]]|$1|W|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|X|$]]

This question is old but still relevant. Slice with length-1 is the best bet, but as an alternative with underscore/lodash:

_.initial() gets all but the last

_.last() gets the last

So you could do 

<pre><code>_.last(_.initial([1,2,3,4])) 
</code></pre>

or chained:

<pre><code>_.chain([1,2,3,4])
 .initial()
 .last()
 .value();
</code></pre>

which gives you back 3.

Or in the original question:

<pre><code>var fragment = '/news/article-1/'
var array_fragment = fragment.split('/');
var pg_url = _.chain(array_fragment).initial().last().value();
</code></pre>

blocks|key|853984|text|如果经常需要反向访问数组，而不仅仅是倒数第二个索引，那么可以使用对原型的简单扩展。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|853985|在扩展像Array+prototype这样大的东西时，请确保您不会影响其使用的任何其他部分。这是通过确保属性不是可枚举的，这样for+in就不会在其他地方阻塞(有些人和库使用for+in来迭代数组)。|offset|length|style|CODE|853986|​|853987|Object.defineProperty(Array.prototype,+'rev',+{
++enumerable:+false,
++value:+function(index){
++++return+this[this.length+-+1+-+index];
++}
});

document.write([1,2,3,4,5,6].rev(1));|code-block|syntax|javascript|853988|853989|现在，您可以反向使用从零开始的索引。|853990|entityMap^0|0|1R|6|2F|6|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|U|8|@$D|V|E|W|F|G]|$D|X|E|Y|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|Z|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|10|8|@]|9|@]|A|$M|N]]|$1|O|3|I|5|6|7|11|8|@]|9|@]|A|$]]|$1|P|3|Q|5|6|7|12|8|@]|9|@]|A|$]]|$1|R|3|-4|5|6|7|13|8|@]|9|@]|A|$]]]|S|$]]

If accessing arrays in reverse is something that is going to be often required, and not just the second to last index, a simple expansion to the prototype could be used.

When extending something as large and used as the Array prototype ensure that you are not going to affect any other part of its use. This is done by making sure that the property is not enumerable so that <code>for in</code> will not choke anywhere else (some people and libraries use <code>for in</code> to iterate arrays).

<div class="snippet" data-lang="js" data-hide="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>Object.defineProperty(Array.prototype, 'rev', {
 enumerable: false,
 value: function(index){
 return this[this.length - 1 - index];
 }
});

document.write([1,2,3,4,5,6].rev(1));</code></pre>
</div>
</div>


And now you can use zero based indexing in reverse.

blocks|key|637492|text|const+myArray:+Array<string>+=+['first',+'second',+'third'];|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|637493|按倒数第二个项目拆分myArray。|unstyled|637494|const+twoItemsFromEnd+=+myArray.slice(-2);+//Outputs:+['second',+'third']|637495|然后|637496|const+secondLast+=+twoItemsFromEnd[0];|637497|或者：|637498|const+secondLast+=+(params.slice(-2))[0];|637499|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|T|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$B|C]]|$1|I|3|J|5|F|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$B|C]]|$1|M|3|N|5|F|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$B|C]]|$1|Q|3|-4|5|F|7|Z|8|@]|9|@]|A|$]]]|R|$]]

<pre><code>const myArray: Array&lt;string&gt; = ['first', 'second', 'third'];
</code></pre>

Split myArray by second last item. 

<pre><code>const twoItemsFromEnd = myArray.slice(-2); //Outputs: ['second', 'third']
</code></pre>

Then

<pre><code>const secondLast = twoItemsFromEnd[0];
</code></pre>

Or:

<pre><code>const secondLast = (params.slice(-2))[0];
</code></pre>

blocks|key|637626|text|var+a+=+[1,2,3,4];
var+b+=+a.slice(-2,-1);
console.log(b);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|637627|答案是3.你只需要提到slice的开始和结束。|unstyled|637628|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>var a = [1,2,3,4];
var b = a.slice(-2,-1);
console.log(b);
</code></pre>

The answer is [3].You just have to mention the start and end for slice.

How can I get the last second item in an array?

For instance,

<pre><code>var fragment = '/news/article-1/'
var array_fragment = fragment.split('/');
var pg_url = $(array_fragment).last()[0];
</code></pre>

This returns an empty value. But I want to get <code>article-1</code>

Thanks.

get the second to last item of an array?

如何获取数组中的最后一秒项？例如,var fragment = '/news/article-1/'var array_fragment = fragment.split('/');var pg_url = $(array_fragment).last()[0];这将返回一个空值。但我想让article-1谢谢。

问获取数组的倒数第二项？
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