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30secondsofcode
2018-12-05 10:24:32 +00:00
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README.md
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@ -6106,6 +6106,7 @@ const sum = (...arr) => [...arr].reduce((acc, val) => acc + val, 0);
<summary>Examples</summary>
```js
sum(1, 2, 3, 4); // 10
sum(...[1, 2, 3, 4]); // 10
```

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docs/math.html
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@ -273,7 +273,8 @@ own individual rating by supplying it as the third argument.
</pre><label class="collapse">examples</label><pre class="section card-examples language-js"><span class="token function">standardDeviation</span><span class="token punctuation">([</span><span class="token number">10</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">38</span><span class="token punctuation">,</span> <span class="token number">23</span><span class="token punctuation">,</span> <span class="token number">38</span><span class="token punctuation">,</span> <span class="token number">23</span><span class="token punctuation">,</span> <span class="token number">21</span><span class="token punctuation">]);</span> <span class="token comment">// 13.284434142114991 (sample)</span>
<span class="token function">standardDeviation</span><span class="token punctuation">([</span><span class="token number">10</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">38</span><span class="token punctuation">,</span> <span class="token number">23</span><span class="token punctuation">,</span> <span class="token number">38</span><span class="token punctuation">,</span> <span class="token number">23</span><span class="token punctuation">,</span> <span class="token number">21</span><span class="token punctuation">],</span> <span class="token boolean">true</span><span class="token punctuation">);</span> <span class="token comment">// 12.29899614287479 (population)</span>
</pre></div><div class="card code-card"><div class="corner beginner"></div><div class="section card-content"><h4 id="sum">sum</h4><p>Returns the sum of two or more numbers/arrays.</p><p>Use <code>Array.prototype.reduce()</code> to add each value to an accumulator, initialized with a value of <code>0</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">sum</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">...</span>arr<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">[</span><span class="token operator">...</span>arr<span class="token punctuation">].</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">)</span> <span class="token operator">=></span> acc <span class="token operator">+</span> val<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">);</span>
</pre><label class="collapse">examples</label><pre class="section card-examples language-js"><span class="token function">sum</span><span class="token punctuation">(</span><span class="token operator">...</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 comment">// 10</span>
</pre><label class="collapse">examples</label><pre class="section card-examples language-js"><span class="token function">sum</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 comment">// 10</span>
<span class="token function">sum</span><span class="token punctuation">(</span><span class="token operator">...</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 comment">// 10</span>
</pre></div><div class="card code-card"><div class="corner intermediate"></div><div class="section card-content"><h4 id="sumby">sumBy</h4><p>Returns the sum of an array, after mapping each element to a value using the provided function.</p><p>Use <code>Array.prototype.map()</code> to map each element to the value returned by <code>fn</code>, <code>Array.prototype.reduce()</code> to add each value to an accumulator, initialized with a value of <code>0</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">sumBy</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> fn<span class="token punctuation">)</span> <span class="token operator">=></span>
arr<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token keyword">typeof</span> fn <span class="token operator">===</span> <span class="token string">'function'</span> <span class="token operator">?</span> fn <span class="token punctuation">:</span> val <span class="token operator">=></span> val<span class="token punctuation">[</span>fn<span class="token punctuation">]).</span><span class="token function">reduce</span><span class="token punctuation">((</span>acc<span class="token punctuation">,</span> val<span class="token punctuation">)</span> <span class="token operator">=></span> acc <span class="token operator">+</span> val<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">);</span>
</pre><label class="collapse">examples</label><pre class="section card-examples language-js"><span class="token function">sumBy</span><span class="token punctuation">([{</span> n<span class="token punctuation">:</span> <span class="token number">4</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">2</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">8</span> <span class="token punctuation">}, {</span> n<span class="token punctuation">:</span> <span class="token number">6</span> <span class="token punctuation">}],</span> o <span class="token operator">=></span> o<span class="token punctuation">.</span>n<span class="token punctuation">);</span> <span class="token comment">// 20</span>