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30secondsofcode
2018-10-10 18:02:26 +00:00
parent b4f3a47908
commit 80ab4013d0
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README.md
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@ -2858,7 +2858,7 @@ Return the last set converted to an array.
```js
const unionBy = (a, b, fn) => {
const s = new Set(a.map(v => fn(v)));
const s = new Set(a.map(fn));
return Array.from(new Set([...a, ...b.filter(x => !s.has(fn(x)))]));
};
```

2
docs/index.html
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@ -543,7 +543,7 @@ managers<span class="token punctuation">;</span> <span class="token comment">//
</pre></div><div class="card code-card"><div class="corner beginner"></div><div class="section card-content"><h4 id="union">union</h4><p>Returns every element that exists in any of the two arrays once.</p><p>Create a <code>Set</code> with all values of <code>a</code> and <code>b</code> and convert to an array.</p></div><div class="copy-button-container"><button class="copy-button" aria-label="Copy to clipboard"></button></div><pre class="section card-code language-js"><span class="token keyword">const</span> <span class="token function-variable function">union</span> <span class="token operator">=</span> <span class="token punctuation">(</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> Array<span class="token punctuation">.</span><span class="token keyword">from</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token class-name">Set</span><span class="token punctuation">([</span><span class="token operator">...</span>a<span class="token punctuation">,</span> <span class="token operator">...</span>b<span class="token punctuation">]));</span>
</pre><label class="collapse">examples</label><pre class="section card-examples language-js"><span class="token function">union</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">], [</span><span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">]);</span> <span class="token comment">// [1,2,3,4]</span>
</pre></div><div class="card code-card"><div class="corner intermediate"></div><div class="section card-content"><h4 id="unionby">unionBy</h4><p>Returns every element that exists in any of the two arrays once, after applying the provided function to each array element of both.</p><p>Create a <code>Set</code> by applying all <code>fn</code> to all values of <code>a</code>. Create a <code>Set</code> from <code>a</code> and all elements in <code>b</code> whose value, after applying <code>fn</code> does not match a value in the previously created set. Return the last set converted to an array.</p></div><div class="copy-button-container"><button class="copy-button" aria-label="Copy to clipboard"></button></div><pre class="section card-code language-js"><span class="token keyword">const</span> <span class="token function-variable function">unionBy</span> <span class="token operator">=</span> <span class="token punctuation">(</span>a<span class="token punctuation">,</span> b<span class="token punctuation">,</span> fn<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
<span class="token keyword">const</span> s <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Set</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span>v <span class="token operator">=></span> <span class="token function">fn</span><span class="token punctuation">(</span>v<span class="token punctuation">)));</span>
<span class="token keyword">const</span> s <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Set</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span>fn<span class="token punctuation">));</span>
<span class="token keyword">return</span> Array<span class="token punctuation">.</span><span class="token keyword">from</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token class-name">Set</span><span class="token punctuation">([</span><span class="token operator">...</span>a<span class="token punctuation">,</span> <span class="token operator">...</span>b<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>x <span class="token operator">=> !</span>s<span class="token punctuation">.</span><span class="token function">has</span><span class="token punctuation">(</span><span class="token function">fn</span><span class="token punctuation">(</span>x<span class="token punctuation">)))]));
};</span>
</pre><label class="collapse">examples</label><pre class="section card-examples language-js"><span class="token function">unionBy</span><span class="token punctuation">([</span><span class="token number">2.1</span><span class="token punctuation">], [</span><span class="token number">1.2</span><span class="token punctuation">,</span> <span class="token number">2.3</span><span class="token punctuation">],</span> Math<span class="token punctuation">.</span>floor<span class="token punctuation">);</span> <span class="token comment">// [2.1, 1.2]</span>