blocks|key|1758857|text|如果您想要selected+=+true的索引，那么可以使用reduce来做类似这样的事情。如果上下文中的当前项具有selected+===+true，则将索引添加到累加器，否则返回累加器。当前，如果条件为false，则添加-1|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1758858|​|1758859|let+options+=+[
++++{label:+'foo1',+selected:+false},
++++{label:+'foo2',+selected:+true},
++++{label:+'foo2',+selected:+false},
++++{label:+'foo2',+selected:+false},
++++{label:+'foo2',+selected:+false},
];

const+selectedIndexes+=+options.reduce((r,+o,+i)+=>+o.selected+?+r.concat(i)+:+r,+[])
console.log(selectedIndexes)|code-block|syntax|javascript|1758860|1758861|如果您想要整个对象，那么您可以简单地使用filter|1758862|1758863|let+options+=+[{label:'foo1',selected:false},{label:'foo2',selected:true},{label:'foo2',selected:false},{label:'foo2',selected:false},{label:'foo2',selected:false},];

const+filtered+=+options.filter(o+=>+o.selected)
console.log(filtered)|1758864|1758865|entityMap^0|5|8|U|6|1M|8|2V|5|34|2|0|0|0|0|K|6|0|0|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|C]|$9|10|A|11|B|C]|$9|12|A|13|B|C]|$9|14|A|15|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|16|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|17|8|@]|D|@]|E|$K|L]]|$1|M|3|G|5|6|7|18|8|@]|D|@]|E|$]]|$1|N|3|O|5|6|7|19|8|@$9|1A|A|1B|B|C]]|D|@]|E|$]]|$1|P|3|G|5|6|7|1C|8|@]|D|@]|E|$]]|$1|Q|3|R|5|J|7|1D|8|@]|D|@]|E|$K|L]]|$1|S|3|G|5|6|7|1E|8|@]|D|@]|E|$]]|$1|T|3|-4|5|6|7|1F|8|@]|D|@]|E|$]]]|U|$]]

<p>If you want indexes with <code>selected</code> = true, then you could do something like this using <code>reduce</code>. If the current item in context has <code>selected</code> === true, add the index to the accumulator, else return the accumulator. Currently, you're adding <code>-1</code> if the condition is <code>false</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>let options = [
    {label: 'foo1', selected: false},
    {label: 'foo2', selected: true},
    {label: 'foo2', selected: false},
    {label: 'foo2', selected: false},
    {label: 'foo2', selected: false},
];

const selectedIndexes = options.reduce((r, o, i) =&gt; o.selected ? r.concat(i) : r, [])
console.log(selectedIndexes)</code></pre>
</div>
</div>
</p>

<p>If you want the whole object, then you can simply use <code>filter</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>let options = [{label:'foo1',selected:false},{label:'foo2',selected:true},{label:'foo2',selected:false},{label:'foo2',selected:false},{label:'foo2',selected:false},];

const filtered = options.filter(o =&gt; o.selected)
console.log(filtered)</code></pre>
</div>
</div>
</p>


blocks|key|5544219|text|仅当option.selected为true时才将索引添加到结果中，否则不执行任何操作。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|5544220|​|5544221|let+options+=+[
++++{label:+'foo1',+selected:+false},
++++{label:+'foo2',+selected:+true},
++++{label:+'foo2',+selected:+false},
++++{label:+'foo2',+selected:+false},
++++{label:+'foo2',+selected:+false},
];

const+selected+=+options.reduce((arr,+option,+index)+=>+{
++return+option.selected+?+arr.concat(index)+:+arr;+
},+[]);

console.log(selected);|code-block|syntax|javascript|5544222|5544223|entityMap^0|2|F|0|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|T|8|@]|D|@]|E|$K|L]]|$1|M|3|G|5|6|7|U|8|@]|D|@]|E|$]]|$1|N|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|O|$]]

<p>Add the index to the result only if <code>option.selected</code> is true otherwise do nothing.</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>let options = [
    {label: 'foo1', selected: false},
    {label: 'foo2', selected: true},
    {label: 'foo2', selected: false},
    {label: 'foo2', selected: false},
    {label: 'foo2', selected: false},
];

const selected = options.reduce((arr, option, index) =&gt; {
  return option.selected ? arr.concat(index) : arr; 
}, []);

console.log(selected);</code></pre>
</div>
</div>
</p>


blocks|key|4076198|text|使用Array#reduce和...扩展操作符保留现有索引，如果selected为true，则添加新索引。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4076199|​|4076200|let+options+=+[
++++{label:+'foo1',+selected:+false},
++++{label:+'foo2',+selected:+true},
++++{label:+'foo2',+selected:+false},
++++{label:+'foo2',+selected:+false},
++++{label:+'foo2',+selected:+false},
++++{label:+'foo2',+selected:+true},
++++{label:+'foo2',+selected:+1}
];

const+obj+=+options.reduce((acc,+currentValue,+index)+=>+{
++++//+checking+only+for+boolean+true+not+for+truthy+values
++++return+acc+=+currentValue["selected"]+===+true+?+[...acc,+index]+:+acc;
},+[]);+
console.log(obj);+|code-block|syntax|javascript|4076201|4076202|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce^0|2|C|F|3|W|8|15|4|2|C|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|C]|$9|10|A|11|B|C]|$9|12|A|13|B|C]]|D|@$9|14|A|15|1|16]]|E|$]]|$1|F|3|G|5|6|7|17|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|18|8|@]|D|@]|E|$K|L]]|$1|M|3|G|5|6|7|19|8|@]|D|@]|E|$]]|$1|N|3|-4|5|6|7|1A|8|@]|D|@]|E|$]]]|O|$P|$5|Q|R|S|E|$T|U]]]]

<p>Using <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce" rel="nofollow noreferrer"><code>Array#reduce</code></a> and the <code>...</code> spread operator keep the existing indexes and add the new index if <code>selected</code> is <code>true</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>let options = [
    {label: 'foo1', selected: false},
    {label: 'foo2', selected: true},
    {label: 'foo2', selected: false},
    {label: 'foo2', selected: false},
    {label: 'foo2', selected: false},
    {label: 'foo2', selected: true},
    {label: 'foo2', selected: 1}
];

const obj = options.reduce((acc, currentValue, index) =&gt; {
    // checking only for boolean true not for truthy values
    return acc = currentValue["selected"] === true ? [...acc, index] : acc;
}, []); 
console.log(obj); </code></pre>
</div>
</div>
</p>


blocks|key|1476537|text|在concat()中使用三元值来设置要插入的值。Array#concat()返回更新后的数组，这就是reduce()的返回值。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1476538|或者使用spread返回新的数组[...accumulator,+selsected+?+i+:-1]|1476539|​|1476540|const+res+=+options.reduce((a,+{selected:s},+i)+=>++a.concat(s+?+i+:+-1)+,+[]);

//+OR
//+const+res+=+options.reduce((a,+{selected:s},+i)+=>++[....a,s+?+i+:+-1]+,+[]);

console.log(res)|code-block|syntax|javascript|1476541|<script>

let+options+=+[
++++{label:+'foo1',+selected:+false},
++++{label:+'foo2',+selected:+true},
++++{label:+'foo2',+selected:+false},
++++{label:+'foo2',+selected:+false},
++++{label:+'foo2',+selected:+false},
];

</script>|1476542|1476543|entityMap^0|1|8|O|E|1E|8|0|G|Z|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@$9|U|A|V|B|C]|$9|W|A|X|B|C]|$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|10|8|@$9|11|A|12|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|13|8|@]|D|@]|E|$]]|$1|J|3|K|5|L|7|14|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|L|7|15|8|@]|D|@]|E|$M|N]]|$1|Q|3|I|5|6|7|16|8|@]|D|@]|E|$]]|$1|R|3|-4|5|6|7|17|8|@]|D|@]|E|$]]]|S|$]]

<p>Use a ternary in <code>concat()</code> to set the value to be inserted. <code>Array#concat()</code> returns the updated array so that is the return for <code>reduce()</code>.</p>

<p>Or use spread to return new array <code>[...accumulator, selsected ? i :-1]</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 res = options.reduce((a, {selected:s}, i) =&gt;  a.concat(s ? i : -1) , []);

// OR
// const res = options.reduce((a, {selected:s}, i) =&gt;  [....a,s ? i : -1] , []);

console.log(res)</code></pre>
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script&gt;

let options = [
    {label: 'foo1', selected: false},
    {label: 'foo2', selected: true},
    {label: 'foo2', selected: false},
    {label: 'foo2', selected: false},
    {label: 'foo2', selected: false},
];

&lt;/script&gt;</code></pre>
</div>
</div>
</p>


blocks|key|4076243|text|另一种方法是使用+push+而不是+|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|CODE|entityRanges|data|4076244|​|4076245|let+options+=+[
++++{label:+'foo1',+selected:+false},
++++{label:+'foo2',+selected:+true},
++++{label:+'foo2',+selected:+false},
++++{label:+'foo2',+selected:+false},
++++{label:+'foo2',+selected:+false},
];

var+obj+=+options.reduce(+(acc,+currentValue,+index)+=>+{
++++currentValue.selected+?+acc.push(index)+:+'';+return+acc}+,[]+)+;

console.log(obj)|code-block|syntax|javascript|4076246|4076247|entityMap^0|9|4|E|3|9|4|0|0|1|0|0|0|1|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|D]]|E|@]|F|$]]|$1|G|3|H|5|6|7|X|8|@$9|Y|A|Z|B|C]]|E|@]|F|$]]|$1|I|3|J|5|K|7|10|8|@]|E|@]|F|$L|M]]|$1|N|3|H|5|6|7|11|8|@$9|12|A|13|B|C]]|E|@]|F|$]]|$1|O|3|-4|5|6|7|14|8|@]|E|@]|F|$]]]|P|$]]

<p><strong><em>Another way is use of <code>push</code> instead of <code>concat</code> :</em></strong></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>let options = [
    {label: 'foo1', selected: false},
    {label: 'foo2', selected: true},
    {label: 'foo2', selected: false},
    {label: 'foo2', selected: false},
    {label: 'foo2', selected: false},
];

var obj = options.reduce( (acc, currentValue, index) =&gt; {
    currentValue.selected ? acc.push(index) : ''; return acc} ,[] ) ;

console.log(obj)</code></pre>
</div>
</div>
</p>


<p>I'm trying to convert this function to use reduce. I am halfway through. When the selected value is <code>true</code> I want to know the index of that element. </p>

<pre><code>let options = [
    {label: 'foo1', selected: false},
    {label: 'foo2', selected: true},
    {label: 'foo2', selected: false},
    {label: 'foo2', selected: false},
    {label: 'foo2', selected: false},
];
const obj = options
              .map((option, index) =&gt; (option.selected ? index : -1))
              .filter((val) =&gt; val !== -1)[0];
</code></pre>

<p>Result: <code>1</code></p>

<p>My attempt is this:</p>

<pre><code>const obj = options.reduce((acc, currentValue, index) =&gt; {
    const i = currentValue["selected"] ? index : -1;
    return acc.concat(i)
}, []); // [-1,1,-1,-1,-1]
</code></pre>

<p>How do I change the entire thing to use reduce?</p>


How to convert this array of objects to use reduce javascript

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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我正在尝试将此函数转换为使用reduce。我已经完成了一半。当选择的值为true时，我想知道该元素的索引。let options = [    {label: 'foo1', selected: false},    {label: 'foo2', selected: true},    {label: 'foo2',...

问如何将此对象数组转换为使用reduce javascript
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问如何将此对象数组转换为使用reduce javascriptEN