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use a Symbol for the key of a Map (rse#82)
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‎features.txt

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@@ -1259,6 +1259,7 @@ Map Data-Structure
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Cleaner data-structure for common algorithms based on maps.
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6| let m = |new Map()|;
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6| let s = |new Symbol()|;
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6| m.|set("hello", 42)|;
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6| m.|set(s, 34)|;
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6| m.|get(s)| === 34;
@@ -1267,6 +1268,7 @@ Cleaner data-structure for common algorithms based on maps.
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6| console.log(key + " = " + val);
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5| var m = |{}|;
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5| // no equivalent in ES5
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5| |m["hello"] = 42|;
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5| // no equivalent in ES5
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5| // no equivalent in ES5

‎index.html

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@@ -1746,6 +1746,7 @@
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<div class="js es6">
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<div class="title"><b>ECMAScript 6</b> &mdash; syntactic sugar: <span class="style reduced">reduced</span> | <span class="style traditional">traditional</span></div>
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<div class="code"><span class="keyword">let</span> m<span class="punctuation"> = </span><span class="mark"><span class="keyword">new</span> Map<span class="punctuation">(</span><span class="punctuation">)</span></span><span class="semi">;</span>
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<span class="keyword">let</span> s<span class="punctuation"> = </span><span class="mark"><span class="keyword">new</span> Symbol<span class="punctuation">(</span><span class="punctuation">)</span></span><span class="semi">;</span>
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m<span class="punctuation">.</span><span class="mark">set<span class="punctuation">(</span><span class="literal">"hello"</span><span class="punctuation">,</span> <span class="literal">42</span><span class="punctuation">)</span></span><span class="semi">;</span>
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m<span class="punctuation">.</span><span class="mark">set<span class="punctuation">(</span>s<span class="punctuation">,</span> <span class="literal">34</span><span class="punctuation">)</span></span><span class="semi">;</span>
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m<span class="punctuation">.</span><span class="mark">get<span class="punctuation">(</span>s<span class="punctuation">)</span></span> <span class="punctuation">===</span> <span class="literal">34</span><span class="semi">;</span>
@@ -1758,7 +1759,8 @@
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</div>
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<div class="arrow"><i class="fa fa-caret-up"></i><i class="fa fa-caret-down"></i></div><div class="js es5">
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<div class="title"><b>ECMAScript 5</b> &mdash; syntactic sugar: <span class="style reduced">reduced</span> | <span class="style traditional">traditional</span></div>
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<div class="code"><span class="keyword">var</span> m<span class="punctuation"> = </span><span class="mark"><span class="punctuation">{</span><span class="punctuation">}</span></span><span class="semi">;</span>
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<div class="code"><span class="keyword">var</span> m<span class="punctuation"> = </span><span class="mark"><span class="punctuation">{</span><span class="punctuation">}</span></span><span class="semi">;</span><span class="comment">
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// no equivalent <span class="keyword">in</span> ES<span class="literal">5</span></span>
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<span class="mark">m<span class="punctuation">[</span><span class="literal">"hello"</span><span class="punctuation">]</span><span class="punctuation"> = </span><span class="literal">42</span></span><span class="semi">;</span><span class="comment">
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// no equivalent <span class="keyword">in</span> ES<span class="literal">5</span></span><span class="comment">
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// no equivalent <span class="keyword">in</span> ES<span class="literal">5</span></span>

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