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30secondsofcode
2019-03-05 18:13:20 +00:00
parent 4c8c417282
commit 08c9806c72
8 changed files with 32 additions and 32 deletions
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8
README.md
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@ -1096,12 +1096,12 @@ difference([1, 2, 3], [1, 2, 4]); // [3]
Returns the difference between two arrays, after applying the provided function to each array element of both.
Create a `Set` by applying `fn` to each element in `b`, then use `Array.prototype.filter()` in combination with `fn` on `a` to only keep values not contained in the previously created set.
Create a `Set` by applying `fn` to each element in `b`, then use `Array.prototype.map()` to apply `fn` to each element in `a`, then `Array.prototype.filter()`
```js
const differenceBy = (a, b, fn) => {
const s = new Set(b.map(fn));
return a.filter(x => !s.has(fn(x)));
return a.map(fn).filter(el => !s.has(el));
};
```
@ -1109,8 +1109,8 @@ const differenceBy = (a, b, fn) => {
<summary>Examples</summary>
```js
differenceBy([2.1, 1.2], [2.3, 3.4], Math.floor); // [1.2]
differenceBy([{ x: 2 }, { x: 1 }], [{ x: 1 }], v => v.x); // [ { x: 2 } ]
differenceBy([2.1, 1.2], [2.3, 3.4], Math.floor); // [1]
differenceBy([{ x: 2 }, { x: 1 }], [{ x: 1 }], v => v.x); // [2]
```
</details>

8
docs/index.html
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@ -135,12 +135,12 @@
<span class="token keyword">return</span> a<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>x<span class="token punctuation">));
};</span>
</pre><label class="collapse">examples</label><pre class="section card-examples language-js"><span class="token function">difference</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">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">]);</span> <span class="token comment">// [3]</span>
</pre></div><div class="card code-card"><div class="corner intermediate"></div><div class="section card-content"><h4 id="differenceby">differenceBy</h4><p>Returns the difference between two arrays, after applying the provided function to each array element of both.</p><p>Create a <code>Set</code> by applying <code>fn</code> to each element in <code>b</code>, then use <code>Array.prototype.filter()</code> in combination with <code>fn</code> on <code>a</code> to only keep values not contained in the previously created set.</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">differenceBy</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>
</pre></div><div class="card code-card"><div class="corner intermediate"></div><div class="section card-content"><h4 id="differenceby">differenceBy</h4><p>Returns the difference between two arrays, after applying the provided function to each array element of both.</p><p>Create a <code>Set</code> by applying <code>fn</code> to each element in <code>b</code>, then use <code>Array.prototype.map()</code> to apply <code>fn</code> to each element in <code>a</code>, then <code>Array.prototype.filter()</code></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">differenceBy</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>b<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> a<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 class="token keyword">return</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 function">filter</span><span class="token punctuation">(</span>el <span class="token operator">=> !</span>s<span class="token punctuation">.</span><span class="token function">has</span><span class="token punctuation">(</span>el<span class="token punctuation">));
};</span>
</pre><label class="collapse">examples</label><pre class="section card-examples language-js"><span class="token function">differenceBy</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> <span class="token number">3.4</span><span class="token punctuation">],</span> Math<span class="token punctuation">.</span>floor<span class="token punctuation">);</span> <span class="token comment">// [1.2]</span>
<span class="token function">differenceBy</span><span class="token punctuation">([{</span> x<span class="token punctuation">:</span> <span class="token number">2</span> <span class="token punctuation">}, {</span> x<span class="token punctuation">:</span> <span class="token number">1</span> <span class="token punctuation">}], [{</span> x<span class="token punctuation">:</span> <span class="token number">1</span> <span class="token punctuation">}],</span> v <span class="token operator">=></span> v<span class="token punctuation">.</span>x<span class="token punctuation">);</span> <span class="token comment">// [ { x: 2 } ]</span>
</pre><label class="collapse">examples</label><pre class="section card-examples language-js"><span class="token function">differenceBy</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> <span class="token number">3.4</span><span class="token punctuation">],</span> Math<span class="token punctuation">.</span>floor<span class="token punctuation">);</span> <span class="token comment">// [1]</span>
<span class="token function">differenceBy</span><span class="token punctuation">([{</span> x<span class="token punctuation">:</span> <span class="token number">2</span> <span class="token punctuation">}, {</span> x<span class="token punctuation">:</span> <span class="token number">1</span> <span class="token punctuation">}], [{</span> x<span class="token punctuation">:</span> <span class="token number">1</span> <span class="token punctuation">}],</span> v <span class="token operator">=></span> v<span class="token punctuation">.</span>x<span class="token punctuation">);</span> <span class="token comment">// [2]</span>
</pre></div><div class="card code-card"><div class="corner intermediate"></div><div class="section card-content"><h4 id="differencewith">differenceWith</h4><p>Filters out all values from an array for which the comparator function does not return <code>true</code>.</p><p>Use <code>Array.prototype.filter()</code> and <code>Array.prototype.findIndex()</code> to find the appropriate values.</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">differenceWith</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> val<span class="token punctuation">,</span> comp<span class="token punctuation">)</span> <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>a <span class="token operator">=></span> val<span class="token punctuation">.</span><span class="token function">findIndex</span><span class="token punctuation">(</span>b <span class="token operator">=></span> <span class="token function">comp</span><span class="token punctuation">(</span>a<span class="token punctuation">,</span> b<span class="token punctuation">))</span> <span class="token operator">=== -</span><span class="token number">1</span><span class="token punctuation">);</span>
</pre><label class="collapse">examples</label><pre class="section card-examples language-js"><span class="token function">differenceWith</span><span class="token punctuation">([</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">1.2</span><span class="token punctuation">,</span> <span class="token number">1.5</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">], [</span><span class="token number">1.9</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">], (</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">=></span> Math<span class="token punctuation">.</span><span class="token function">round</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span> <span class="token operator">===</span> Math<span class="token punctuation">.</span><span class="token function">round</span><span class="token punctuation">(</span>b<span class="token punctuation">));</span> <span class="token comment">// [1, 1.2]</span>
</pre></div><div class="card code-card"><div class="corner beginner"></div><div class="section card-content"><h4 id="drop">drop</h4><p>Returns a new array with <code>n</code> elements removed from the left.</p><p>Use <code>Array.prototype.slice()</code> to slice the remove the specified number of elements from the left.</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">drop</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> n <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span>n<span class="token punctuation">);</span>

2
test/_30s.js
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@ -260,7 +260,7 @@ const difference = (a, b) => {
};
const differenceBy = (a, b, fn) => {
const s = new Set(b.map(fn));
return a.filter(x => !s.has(fn(x)));
return a.map(fn).filter(el => !s.has(el));
};
const differenceWith = (arr, val, comp) => arr.filter(a => val.findIndex(b => comp(a, b)) === -1);
const dig = (obj, target) =>