blocks|key|3993056|text|将每组的第一个对象展开到结果对象中，得到递归属性：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3993057|​|3993058|const+taxItems+=+[{"taxCode":"430","taxAmount":2,"ItemTaxPercentage":20,"taxCategory":"2"},{"taxCode":"430","taxAmount":4,"ItemTaxPercentage":20,"taxCategory":"2"},{"taxCode":"431","taxAmount":5,"ItemTaxPercentage":20,"taxCategory":"2"},{"taxCode":"430","taxAmount":6,"ItemTaxPercentage":20,"taxCategory":"2"}];

const+results+=+_(taxItems)
++.groupBy('taxCode')
++.map((objs,+taxCode)+=>+({
++++++..._.head(objs),
++++++taxCode,
++++++taxAmount:+_.sumBy(objs,+'taxAmount')+}))
++.value();
++
console.log(results);|code-block|syntax|javascript|3993059|<script+src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>|3993060|3993061|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|P|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|K|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|L|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|M|$]]

<p>Spread the 1st object of each group into the result object, to get the recurring properties:</p>

<p><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>const taxItems = [{"taxCode":"430","taxAmount":2,"ItemTaxPercentage":20,"taxCategory":"2"},{"taxCode":"430","taxAmount":4,"ItemTaxPercentage":20,"taxCategory":"2"},{"taxCode":"431","taxAmount":5,"ItemTaxPercentage":20,"taxCategory":"2"},{"taxCode":"430","taxAmount":6,"ItemTaxPercentage":20,"taxCategory":"2"}];

const results = _(taxItems)
  .groupBy('taxCode')
  .map((objs, taxCode) =&gt; ({
      ..._.head(objs),
      taxCode,
      taxAmount: _.sumBy(objs, 'taxAmount') }))
  .value();
  
console.log(results);</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.min.js"&gt;&lt;/script&gt;</code></pre>
</div>
</div>
</p>


blocks|key|3993106|text|这将会起作用。只需一个简单的reduce。为此，您不需要使用lodash。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3993107|const+results+=+taxItems.reduce(function(sum,+taxItem)+{

++++let+index+=+sum.map(item+=>+item.taxCode).indexOf(taxItem.taxCode);
++++if+(index+==+-1)+{
++++++++sum.push(taxItem);
++++}+else+{
++++++++sum[index].taxAmount+=+sum[index].taxAmount+%2B+taxItem.taxAmount;
++++}

++++return+sum;
},+[]);

//results+
//[{"taxCode":"430","taxAmount":12,"ItemTaxPercentage":20,"taxCategory":"2"}{"taxCode":"431","taxAmount":5,"ItemTaxPercentage":20,"taxCategory":"2"}]|code-block|syntax|javascript|3993108|entityMap^0|U|6|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

<p>This will work. with a simple reduce. you don't need to use <code>lodash</code> for this. </p>

<pre><code>const results = taxItems.reduce(function(sum, taxItem) {

    let index = sum.map(item =&gt; item.taxCode).indexOf(taxItem.taxCode);
    if (index == -1) {
        sum.push(taxItem);
    } else {
        sum[index].taxAmount = sum[index].taxAmount + taxItem.taxAmount;
    }

    return sum;
}, []);

//results 
//[{"taxCode":"430","taxAmount":12,"ItemTaxPercentage":20,"taxCategory":"2"}{"taxCode":"431","taxAmount":5,"ItemTaxPercentage":20,"taxCategory":"2"}]
</code></pre>


blocks|key|3990003|text|你也可以通过_.map，_.groupBy和_.mergeWith来解决这个问题|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3990004|​|3990005|const+taxItems+=+[{+taxCode:+'430',+taxAmount:+2,+ItemTaxPercentage:+20,+taxCategory:+'2'+},+{+taxCode:+'430',+taxAmount:+4,+ItemTaxPercentage:+20,+taxCategory:+'2'+},+{+taxCode:+'431',+taxAmount:+5,+ItemTaxPercentage:+20,+taxCategory:+'2'+},+{+taxCode:+'430',+taxAmount:+6,+ItemTaxPercentage:+20,+taxCategory:+'2'+}+]

const+result+=+_.map(_.groupBy(taxItems,+'taxCode'),+x+=>+
++_.mergeWith(...x,+(o,s,k)+=>+k+==+'taxAmount'+?+o%2Bs+:+s))

console.log(result)|code-block|syntax|javascript|3990006|<script+src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.min.js"></script>|3990007|3990008|entityMap^0|6|5|C|9|M|B|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]|$9|W|A|X|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Y|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|Z|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|O|3|G|5|6|7|11|8|@]|D|@]|E|$]]|$1|P|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|Q|$]]

<p>You could also solve this via <code>_.map</code>, <code>_.groupBy</code> and <code>_.mergeWith</code>:</p>

<p><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>const taxItems = [{ taxCode: '430', taxAmount: 2, ItemTaxPercentage: 20, taxCategory: '2' }, { taxCode: '430', taxAmount: 4, ItemTaxPercentage: 20, taxCategory: '2' }, { taxCode: '431', taxAmount: 5, ItemTaxPercentage: 20, taxCategory: '2' }, { taxCode: '430', taxAmount: 6, ItemTaxPercentage: 20, taxCategory: '2' } ]

const result = _.map(_.groupBy(taxItems, 'taxCode'), x =&gt; 
  _.mergeWith(...x, (o,s,k) =&gt; k == 'taxAmount' ? o+s : s))

console.log(result)</code></pre>
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.min.js"&gt;&lt;/script&gt;</code></pre>
</div>
</div>
</p>


<p>I cannot find solution to this problem.</p>

<p>I have array:</p>

<pre class="lang-js prettyprint-override"><code>const taxItems = [{
    taxCode: '430',
    taxAmount: 2,
    ItemTaxPercentage: 20,
    taxCategory: '2'
  },
  {
    taxCode: '430',
    taxAmount: 4,
    ItemTaxPercentage: 20,
    taxCategory: '2'
  },
  {
    taxCode: '431',
    taxAmount: 5,
    ItemTaxPercentage: 20,
    taxCategory: '2'
  },
  {
    taxCode: '430',
    taxAmount: 6,
    ItemTaxPercentage: 20,
    taxCategory: '2'
  }
]
</code></pre>

<p>And from this array I want to sum up all objects by taxCode.I want to have results like this:</p>

<pre><code>var results = [{
    taxCode: '430',
    taxAmount: 12,
    ItemTaxPercentage: 20,
    taxCategory: '2'
  },
  {
    taxCode: '431',
    taxAmount: 5,
    ItemTaxPercentage: 20,
    taxCategory: '2'
  }
]
</code></pre>



<p>I tried to use lodash:</p>

<pre><code>var results =
lodash(taxItems)
  .groupBy('taxCode')
  .map((objs, key) =&gt; ({
      'taxCode': key,
      'taxAmount': lodash.sumBy(objs, 'taxAmount') }))
  .value();
</code></pre>

<p>But it only works with key value pair. I will loose the original structure of the object. </p>

<p>What would be the correct solution to my problem?</p>


How to sum up object values in array by some key?

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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我找不到解决这个问题的办法。我有数组：const taxItems = [{    taxCode: '430',    taxAmount: 2,    ItemTaxPercentage: 20,    taxCategory: '2'  },  {    taxCode: '430',    taxAmount:...

问如何通过某个键对数组中的对象值求和？
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问如何通过某个键对数组中的对象值求和？
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