blocks|key|463953|text|下面是使用类似于Java+map的东西的一种简单方便的方法|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|463954|var+map=+{
++++'map_name_1':+map_value_1,
++++'map_name_2':+map_value_2,
++++'map_name_3':+map_value_3,
++++'map_name_4':+map_value_4
++++}|code-block|syntax|javascript|463955|并获取该值：|463956|alert(+map['map_name_1']+);++++//+fives+the+value+of+map_value_1

......++etc++.....|463957|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/7/docs/api/java/util/Map.html^0|D|3|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|C|$]]|$1|K|3|L|5|F|7|10|8|@]|9|@]|C|$G|H]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

<p>Here is an easy and convenient way of using something similar to the Java <a href="http://docs.oracle.com/javase/7/docs/api/java/util/Map.html" rel="noreferrer">map</a>:</p>

<pre><code>var map= {
    'map_name_1': map_value_1,
    'map_name_2': map_value_2,
    'map_name_3': map_value_3,
    'map_name_4': map_value_4
    }
</code></pre>

<p>And to get the value:</p>

<pre><code>alert( map['map_name_1'] );    // fives the value of map_value_1

......  etc  .....
</code></pre>


blocks|key|679071|text|<html>
<head>
<script+type="text/javascript">
function+test(){
var+map=+{'m1':+12,'m2':+13,'m3':+14,'m4':+15}
+++++alert(map['m3']);
}
</script>
</head>
<body>
<input+type="button"+value="click"+onclick="test()"/>
</body>
</html>|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|679072|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>&lt;html&gt;
&lt;head&gt;
&lt;script type="text/javascript"&gt;
function test(){
var map= {'m1': 12,'m2': 13,'m3': 14,'m4': 15}
     alert(map['m3']);
}
&lt;/script&gt;
&lt;/head&gt;
&lt;body&gt;
&lt;input type="button" value="click" onclick="test()"/&gt;
&lt;/body&gt;
&lt;/html&gt;
</code></pre>


blocks|key|679095|text|你应该尝试这个Map类吗？|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|679096|​|679097|var+myMap+=+new+Map();

//+setting+the+values
myMap.set("1",+'value1');
myMap.set("2",+'value2');
myMap.set("3",+'value3');

console.log(`Map+size:+${myMap.size}`);+//+3

//+getting+the+values
console.log(`Key:+"1",+Value:+${myMap.get("1")}`);++++//+"value+associated+with+"value1"
console.log(`Key:+"2",+Value:+${myMap.get("2")}`);++++//+"value+associated+with+"value2"
console.log(`Key:+"3",+Value:+${myMap.get("3")}`);++++//+"value+associated+with+"value3"|code-block|syntax|javascript|679098|679099|注意：key和value可以是任何类型。|679100|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map|679101|entityMap|0|LINK|mutability|MUTABLE|url^0|7|3|0|0|0|0|3|3|7|5|0|0|2C|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|11|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|12|8|@]|D|@]|E|$K|L]]|$1|M|3|G|5|6|7|13|8|@]|D|@]|E|$]]|$1|N|3|O|5|6|7|14|8|@$9|15|A|16|B|C]|$9|17|A|18|B|C]]|D|@]|E|$]]|$1|P|3|Q|5|6|7|19|8|@]|D|@$9|1A|A|1B|1|1C]]|E|$]]|$1|R|3|-4|5|6|7|1D|8|@]|D|@]|E|$]]]|S|$T|$5|U|V|W|E|$X|Q]]]]

<p>Should you try this class <code>Map</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>var myMap = new Map();

// setting the values
myMap.set("1", 'value1');
myMap.set("2", 'value2');
myMap.set("3", 'value3');

console.log(`Map size: ${myMap.size}`); // 3

// getting the values
console.log(`Key: "1", Value: ${myMap.get("1")}`);    // "value associated with "value1"
console.log(`Key: "2", Value: ${myMap.get("2")}`);    // "value associated with "value2"
console.log(`Key: "3", Value: ${myMap.get("3")}`);    // "value associated with "value3"</code></pre>
</div>
</div>
</p>
<p>Notice: <code>key</code> and <code>value</code> can be any type.</p>
<p><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map" rel="nofollow noreferrer">https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map</a></p>


blocks|key|679150|text|我遇到了一个问题，我有一个带有一些公共密钥的json。我想对具有相同键的所有值进行分组。在网上冲浪后，我找到了hashmap+package。这真的很有帮助。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|679151|为了使用相同的键对元素进行分组，我使用了multi(key:*,+value:*,+key2:*,+value2:*,+...)。|style|CODE|679152|这个包有点类似于Java+Hashmap集合，但没有Java+Hashmap强大。|679153|entityMap|0|LINK|mutability|MUTABLE|url|https://www.npmjs.com/package/hashmap^0|1J|F|0|0|K|18|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@$A|S|B|T|1|U]]|C|$]]|$1|D|3|E|5|6|7|V|8|@$A|W|B|X|F|G]]|9|@]|C|$]]|$1|H|3|I|5|6|7|Y|8|@]|9|@]|C|$]]|$1|J|3|-4|5|6|7|Z|8|@]|9|@]|C|$]]]|K|$L|$5|M|N|O|C|$P|Q]]]]

<p>I was running into the problem where i had the json with some common keys. I wanted to group all the values having the same key. After some surfing I found <a href="https://www.npmjs.com/package/hashmap" rel="nofollow noreferrer">hashmap package</a>. Which is really helpful.</p>

<p>To group the element with the same key, I used <code>multi(key:*, value:*, key2:*, value2:*, ...)</code>.</p>

<p>This package is somewhat similar to Java Hashmap collection, but not as powerful as Java Hashmap.</p>


<p>I currently work with OpenLayers and have a huge set of data to draw into a vector layer (greater than 100000 vectors).</p>

<p>I'm now trying to put all these vectors into a JavaScript hash map to analyze the performance.  I want to know how is the hash map in JavaScript implemented, is it a real hash function or just a wrapped function that uses a simple data structure and a search algorithm?</p>


How is a JavaScript hash map implemented?

数据结构

Java

我目前使用的是OpenLayers，有大量的数据要绘制到一个矢量层(大于100000个矢量)。我现在正尝试将所有这些向量放入一个JavaScript散列图中，以分析性能。我想知道JavaScript中的散列映射是如何实现的，它是一个真正的散列函数，还是只是一个使用简单数据结构和搜索算法的包装函数？

问JavaScript散列映射是如何实现的？
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