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    <title>DEV Community: 阳同尘</title>
    <description>The latest articles on DEV Community by 阳同尘 (@jarry).</description>
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      <title>DEV Community: 阳同尘</title>
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    <item>
      <title>JS array's unique</title>
      <dc:creator>阳同尘</dc:creator>
      <pubDate>Wed, 02 Sep 2020 09:21:55 +0000</pubDate>
      <link>https://dev.to/jarry/js-array-s-unique-1m10</link>
      <guid>https://dev.to/jarry/js-array-s-unique-1m10</guid>
      <description>&lt;p&gt;How to remove duplication item from JS array?&lt;br&gt;
Here is 18 methods.&lt;br&gt;
&lt;a href="https://github.com/microwind/algorithms/tree/master/unique"&gt;https://github.com/microwind/algorithms/tree/master/unique&lt;/a&gt;&lt;/p&gt;

&lt;p&gt;// the multi method for array unique&lt;br&gt;
// JavaScript数组去重的N种方法&lt;br&gt;
(function () {&lt;br&gt;
  // 1. new array&lt;br&gt;
  console.time('time')&lt;br&gt;
  var arr = ['a', 'a', 1, 1, 2, 2, 'b', 'b', 2, 1]&lt;br&gt;
  var newArr = []&lt;br&gt;
  for (var i = 0, l = arr.length; i &amp;lt; l; i++) {&lt;br&gt;
    for (var j = 0; j &amp;lt;= i; j++) {&lt;br&gt;
      if (arr[i] === arr[j]) {&lt;br&gt;
        if (i === j) {&lt;br&gt;
          newArr.push(arr[i])&lt;br&gt;
        }&lt;br&gt;
        break&lt;br&gt;
      }&lt;br&gt;
    }&lt;br&gt;
  }&lt;br&gt;
  console.log('new array result:', newArr)&lt;br&gt;
  console.timeEnd('time')&lt;br&gt;
})();&lt;/p&gt;

&lt;p&gt;(function () {&lt;br&gt;
  // 1.1 new array + indexOf&lt;br&gt;
  console.time('time')&lt;br&gt;
  var arr = ['a', 'a', 1, 1, 2, 2, 'b', 'b', 2, 1]&lt;br&gt;
  var newArr = []&lt;br&gt;
  for (var i = 0, l = arr.length; i &amp;lt; l; i++) {&lt;br&gt;
    if (newArr.indexOf(arr[i]) &amp;lt; 0) {&lt;br&gt;
      newArr.push(arr[i])&lt;br&gt;
    }&lt;br&gt;
  }&lt;br&gt;
  console.log('new array + indexOf:', newArr)&lt;br&gt;
  console.timeEnd('time')&lt;br&gt;
})();&lt;/p&gt;

&lt;p&gt;(function () {&lt;br&gt;
  // 1.2 new array + includes&lt;br&gt;
  console.time('time')&lt;br&gt;
  var arr = ['a', 'a', 1, 1, 2, 2, 'b', 'b', 2, 1]&lt;br&gt;
  var newArr = []&lt;br&gt;
  for (var i = 0, l = arr.length; i &amp;lt; l; i++) {&lt;br&gt;
    if (!newArr.includes(arr[i])) {&lt;br&gt;
      newArr.push(arr[i])&lt;br&gt;
    }&lt;br&gt;
  }&lt;br&gt;
  console.log('new array + includes:', newArr)&lt;br&gt;
  console.timeEnd('time')&lt;br&gt;
})();&lt;/p&gt;

&lt;p&gt;more see: &lt;a href="https://github.com/microwind/algorithms/tree/master/unique"&gt;https://github.com/microwind/algorithms/tree/master/unique&lt;/a&gt;&lt;/p&gt;

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      <category>javascript</category>
      <category>unique</category>
      <category>duplicate</category>
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