blocks|key|1418196|text|var+a+=+[4,6,12];
var+b+=+[4,6];

for+(var+i+=+0;+i+<+a.length;+i%2B%2B)+{
+++++++if+(!b.indexOf(a[i]))+{
+++++++++a.pop();
+++++++}
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1418197|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>var a = [4,6,12];
var b = [4,6];

for (var i = 0; i &lt; a.length; i++) {
 if (!b.indexOf(a[i])) {
 a.pop();
 }
}
</code></pre>

blocks|key|1642956|text|var+a+=+[4,6,12];
var+b+=+[4,6];

var+common+=+$.grep(a,+function(element)+{
++++return+$.inArray(element,+b+)+!==+-1;
});

console.log(common);+//+returns+[4,6];|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1642957|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>var a = [4,6,12];
var b = [4,6];

var common = $.grep(a, function(element) {
 return $.inArray(element, b ) !== -1;
});

console.log(common); // returns [4,6];
</code></pre>

blocks|key|5427350|text|a出现为空的原因是因为您的双循环。您正在将a的每个元素与b的每个其他元素进行比较。当你点击==+b1时，很明显，4+!=+6，所以你会弹出它。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|5427351|entityMap^0|0|1|L|1|S|1|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|O|8|@]|D|@]|E|$]]]|G|$]]

The reason why <code>a</code> is coming out as empty is because of your double loop. You're comparing each element of <code>a</code> to every other element of <code>b</code>. When you hit a[0] == b[1], obviously, 4 != 6 so you pop it.

blocks|key|5427361|text|试试这个：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5427362|var+a+=+[4,6,12];
var+b+=+[4,6];
var+i+=+0;
for+(;+i+<+a.length+&&+i+<+b.length;+i%2B%2B)
++++if+(a[i]+!==+b[i])+{
++++++++a.pop();
++++++++break;
++++}
while(i+<+a.length)
++++a.pop();|code-block|syntax|javascript|5427363|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Try this:

<pre><code>var a = [4,6,12];
var b = [4,6];
var i = 0;
for (; i &lt; a.length &amp;&amp; i &lt; b.length; i++)
 if (a[i] !== b[i]) {
 a.pop();
 break;
 }
while(i &lt; a.length)
 a.pop();
</code></pre>

blocks|key|1642988|text|a+=+a.filter(function(item){+return+b.contains(item);+});|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1642989|More+on+.filter()|unstyled|offset|length|1642990|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter^0|0|0|H|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|R|8|@]|9|@$G|S|H|T|1|U]]|A|$]]|$1|I|3|-4|5|F|7|V|8|@]|9|@]|A|$]]]|J|$K|$5|L|M|N|A|$O|P]]]]

<pre><code>a = a.filter(function(item){ return b.contains(item); });
</code></pre>

<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter" rel="nofollow">More on .filter()</a>

blocks|key|1643031|text|您的第二个for循环会导致此脚本删除a：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1643032|1.+i+=+0,+j+=+0+=>+a[0]+=+4,+b[0]+=+4.+(4+!==+4)+=>+false,+
2.+i+=+0,+j+=+1+=>+a[0]+=+4,+b[1]+=+6.+(4+!==+6)+=>+true,+pop+first+element+from+a
3.+i+=+1,+j+=+0+=>+a[1]+=+6,+b[0]+=+4.+(6+!==+4)+=>+true,+pop+second+elmement+from+a|code-block|syntax|javascript|1643033|因此，您从a中弹出一个元素，直到a为空。|1643034|相反，尝试：|1643035|var+a+=+[4,6,12];
var+b+=+[4,6];

++++for+(var+i+=+0;+i+<+a.length;+i%2B%2B)+{
+++++++++++if+(b.indexOf(a[i])+==+-1)+{
+++++++++++++a.pop();

++++++++}
++++}|1643036|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|S|8|@]|9|@]|A|$E|F]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Your second for-loop causes this script to remove everything from a: 

<pre><code>1. i = 0, j = 0 =&gt; a[0] = 4, b[0] = 4. (4 !== 4) =&gt; false, 
2. i = 0, j = 1 =&gt; a[0] = 4, b[1] = 6. (4 !== 6) =&gt; true, pop first element from a
3. i = 1, j = 0 =&gt; a[1] = 6, b[0] = 4. (6 !== 4) =&gt; true, pop second elmement from a
</code></pre>

So you are popping one element after another from a until a is empty.

Try instead: 

<pre><code>var a = [4,6,12];
var b = [4,6];

 for (var i = 0; i &lt; a.length; i++) {
 if (b.indexOf(a[i]) == -1) {
 a.pop();

 }
 }
</code></pre>

I have the following 

<pre><code>var a = [4,6,12];
var b = [4,6];

for (var i = 0; i &lt; a.length; i++) {
 for (var j = 0; j &lt; b.length; j++) {
 if (a[i] !== b[j]) {
 a.pop();
 }
 }
}
</code></pre>

I want to compare the two and remove 12 from a if it is not found in b. I do not want to create a new array with the result just remove from a.

However, if I console log a I get a as empty.

Compare array js

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我有以下几点var a = [4,6,12];var b = [4,6];for (var i = 0; i < a.length; i++) { for (var j = 0; j < b.length; j++) { if (a[i] !== b[j]) { a.pop(); ...

问比较数组js
EN

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