blocks|key|1538820|text|有一个slice方法|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1538821|​|1538822|let+arr+=+[1,+2,+3,+4,+5,+6,+7,+8,+9,+10]
arr+=+arr.slice(0,+4);
console.log(arr);|code-block|syntax|javascript|1538823|1538824|将返回前四个元素。|1538825|如果你想丢弃其他的值，不要忘了把它赋值回你的变量。|1538826|注意:这只是普通的javascript，不需要jquery。|1538827|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice^0|3|5|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@$A|10|B|11|1|12]]|C|$]]|$1|D|3|E|5|6|7|13|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|14|8|@]|9|@]|C|$I|J]]|$1|K|3|E|5|6|7|15|8|@]|9|@]|C|$]]|$1|L|3|M|5|6|7|16|8|@]|9|@]|C|$]]|$1|N|3|O|5|6|7|17|8|@]|9|@]|C|$]]|$1|P|3|Q|5|6|7|18|8|@]|9|@]|C|$]]|$1|R|3|-4|5|6|7|19|8|@]|9|@]|C|$]]]|S|$T|$5|U|V|W|C|$X|Y]]]]

There is a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice" rel="noreferrer">slice</a> method
<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>let arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
arr = arr.slice(0, 4);
console.log(arr);</code></pre>
</div>
</div>

Will return the first four elements.
Don't forget to assign it back to your variable if you want to discard the other values.
Note: This is just regular javascript, no need for jquery.

blocks|key|1323658|text|如果您既要获取元素，又要从数组中删除它们，请使用splice。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1323659|如果希望保留数组中的元素，请使用slice|1323660|entityMap|0|LINK|mutability|MUTABLE|url|http://www.w3schools.com/jsref/jsref_splice.asp|1|http://www.w3schools.com/jsref/jsref_slice_array.asp^0|O|6|0|0|G|5|1|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@$A|Q|B|R|1|S]]|C|$]]|$1|D|3|E|5|6|7|T|8|@]|9|@$A|U|B|V|1|W]]|C|$]]|$1|F|3|-4|5|6|7|X|8|@]|9|@]|C|$]]]|G|$H|$5|I|J|K|C|$L|M]]|N|$5|I|J|K|C|$L|O]]]]

If you want to both get the elements as well as remove them from the array, use <a href="http://www.w3schools.com/jsref/jsref_splice.asp" rel="noreferrer">splice</a>.

If you want to keep the elements in the array, use <a href="http://www.w3schools.com/jsref/jsref_slice_array.asp" rel="noreferrer">slice</a>

blocks|key|1538896|text|如果想要有选择地从数组中提取元素，可以使用jQuery.grep方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1538897|(来自jQuery文档)|1538898|var+arr+=+[+1,+9,+3,+8,+6,+1,+5,+9,+4,+7,+3,+8,+6,+9,+1+];

$("div").text(arr.join(",+"));

arr+=+jQuery.grep(arr,+function(n,+i){
++return+(n+!=+5+&&+i+>+4);
});

$("p").text(arr.join(",+"));

arr+=+jQuery.grep(arr,+function+(a)+{+return+a+!=+9;+});
$("span").text(arr.join(",+"));|code-block|syntax|javascript|1538899|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.jquery.com/Utilities/jQuery.grep#arraycallbackinvert^0|L|B|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|C|$I|J]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

If you want to selectively pull elements out of an array, you can use the <a href="http://docs.jquery.com/Utilities/jQuery.grep#arraycallbackinvert" rel="nofollow noreferrer">jQuery.grep</a> method.

(from the jQuery docs)

<pre><code>var arr = [ 1, 9, 3, 8, 6, 1, 5, 9, 4, 7, 3, 8, 6, 9, 1 ];

$("div").text(arr.join(", "));

arr = jQuery.grep(arr, function(n, i){
 return (n != 5 &amp;&amp; i &gt; 4);
});

$("p").text(arr.join(", "));

arr = jQuery.grep(arr, function (a) { return a != 9; });
$("span").text(arr.join(", "));
</code></pre>

blocks|key|1323722|text|如果您正在询问如何截断(通过删除末尾的元素来修改数组)，那么可以使用splice|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1323723|var+a1+=+[2,4,6,8];
var+a2+=+a1.splice(-2,2);+//+a1=[2,4],+a2=[6,8]|code-block|syntax|javascript|1323724|如果您正在询问如何在不修改原始数组的情况下检索数组的子集，那么使用slice。|1323725|var+a1+=+[2,4,6,8];
var+a2+=+a1.slice(-2);+//+a1=[2,4,6,8],+a2=[6,8]|1323726|只需记住拼接修改，切片访问。负数作为第一个参数表示从数组末尾开始的索引。|1323727|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Array/splice|1|https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Array/slice^0|Y|6|0|0|0|X|5|1|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@$A|Z|B|10|1|11]]|C|$]]|$1|D|3|E|5|F|7|12|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|13|8|@]|9|@$A|14|B|15|1|16]]|C|$]]|$1|K|3|L|5|F|7|17|8|@]|9|@]|C|$G|H]]|$1|M|3|N|5|6|7|18|8|@]|9|@]|C|$]]|$1|O|3|-4|5|6|7|19|8|@]|9|@]|C|$]]]|P|$Q|$5|R|S|T|C|$U|V]]|W|$5|R|S|T|C|$U|X]]]]

If you're asking how to truncate (modify an array by removing the elements from the end) then use <a href="https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Array/splice" rel="noreferrer">splice</a>:

<pre><code>var a1 = [2,4,6,8];
var a2 = a1.splice(-2,2); // a1=[2,4], a2=[6,8]
</code></pre>

If you're asking how to retrieve a subset of an array without modifying the original, then use <a href="https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Array/slice" rel="noreferrer">slice</a>.

<pre><code>var a1 = [2,4,6,8];
var a2 = a1.slice(-2); // a1=[2,4,6,8], a2=[6,8]
</code></pre>

Just remember splice modifies, slice accesses. Negative numbers as first arg indicate index from the end of the array.

blocks|key|1538960|text|将.length属性设置为较低的值。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1538961|官方文档：Array.prototype.length|offset|length|1538962|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/length^0|0|5|M|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@$D|P|E|Q|1|R]]|A|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|G|$H|$5|I|J|K|A|$L|M]]]]

Set .length property to a lower value.

Official documentation:
<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/length">Array.prototype.length</a>

blocks|key|1539018|text|如果您使用的是are+(3)，我将假设数组最初被定义为参数3|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1539019|const+result+=+new+Array(3)+
//+result+=+[undefined+,+undefined+,+undefined]|code-block|syntax|javascript|1539020|如果您的迭代器只返回2个值，或者这些值在使用are+(3)命令后被过滤，并且删除了其中的一个值，则数组将如下所示|1539021|//result+=+[1+,+1+,+undefined]|1539022|因此，要截断空元素的数组，可以使用|1539023|+result.filter((value)+=>+value+!==+undefined);|1539024|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

If you are using a take(3), I'm going to assume the array is originally being defined as the argument 3
<pre><code>const result = new Array(3) 
// result = [undefined , undefined , undefined]
</code></pre>
If you iterator only returns 2 values, or the values are filtered after the take(3) command and 1 of your values is removed the array would look like
<pre><code>//result = [1 , 1 , undefined]
</code></pre>
so to truncate the array of empty elements you can use
<pre><code> result.filter((value) =&gt; value !== undefined);
</code></pre>

Linq has a convenient operator method called <code>Take()</code> to return a given number of elements in anything that implements <code>IEnumerable</code>. Is there anything similar in jQuery for working with arrays?
Or, asked differently: how can I truncate an array in Javascript?

How to easily truncate an array with JavaScript?

jQuery

IEnumerable有一个方便的操作符方法，称为Take()，它可以在实现Linq的任何东西中返回给定数量的元素。在jQuery中有没有类似的处理数组的东西？或者，换一种方式问:我如何截断Javascript中的数组？

问如何使用JavaScript轻松截断数组？
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