andre/30-seconds-of-code
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Travis build: 2063

Browse Source
This commit is contained in:
30secondsofcode
2018-05-15 18:49:13 +00:00
parent f68a5346df
commit d876446df3
2 changed files with 6 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
README.md
View File

@ -1255,14 +1255,14 @@ findLast([1, 2, 3, 4], n => n % 2 === 1); // 3
Returns the index of the last element for which the provided function returns a truthy value.
Use `Array.map()` to map each element to an array with its index and value.
Use `Array.filter()` to remove elements for which `fn` returns falsey values, `Array.slice(-1)` to get the last one.
Use `Array.filter()` to remove elements for which `fn` returns falsey values, `Array.pop()` to get the last one.
```js
const findLastIndex = (arr, fn) =>
arr
.map((val, i) => [i, val])
.filter(val => fn(val[1], val[0], arr))
.slice(-1)[0][0];
.filter(([i, val]) => fn(val, i, arr))
.pop()[0];
```
<details>

6
docs/array.html
View File

@ -146,11 +146,11 @@
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">filterNonUnique</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">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">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">]);</span> <span class="token comment">// [1,3,5]</span>
</pre><button class="primary clipboard-copy">&#128203;&nbsp;Copy to clipboard</button></div></div><div class="card fluid"><h3 id="findlast" class="section double-padded">findLast</h3><div class="section double-padded"><p>Returns the last element for which the provided function returns a truthy value.</p><p>Use <code>Array.filter()</code> to remove elements for which <code>fn</code> returns falsey values, <code>Array.pop()</code> to get the last one.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">findLast</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">filter</span><span class="token punctuation">(</span>fn<span class="token punctuation">).</span><span class="token function">pop</span><span class="token punctuation">();</span>
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">findLast</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> n <span class="token operator">=></span> n <span class="token operator">%</span> <span class="token number">2</span> <span class="token operator">===</span> <span class="token number">1</span><span class="token punctuation">);</span> <span class="token comment">// 3</span>
</pre><button class="primary clipboard-copy">&#128203;&nbsp;Copy to clipboard</button></div></div><div class="card fluid"><h3 id="findlastindex" class="section double-padded">findLastIndex</h3><div class="section double-padded"><p>Returns the index of the last element for which the provided function returns a truthy value.</p><p>Use <code>Array.map()</code> to map each element to an array with its index and value. Use <code>Array.filter()</code> to remove elements for which <code>fn</code> returns falsey values, <code>Array.slice(-1)</code> to get the last one.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">findLastIndex</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>
</pre><button class="primary clipboard-copy">&#128203;&nbsp;Copy to clipboard</button></div></div><div class="card fluid"><h3 id="findlastindex" class="section double-padded">findLastIndex</h3><div class="section double-padded"><p>Returns the index of the last element for which the provided function returns a truthy value.</p><p>Use <code>Array.map()</code> to map each element to an array with its index and value. Use <code>Array.filter()</code> to remove elements for which <code>fn</code> returns falsey values, <code>Array.pop()</code> to get the last one.</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">findLastIndex</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>val<span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">[</span>i<span class="token punctuation">,</span> val<span class="token punctuation">])
.</span><span class="token function">filter</span><span class="token punctuation">(</span>val <span class="token operator">=></span> <span class="token function">fn</span><span class="token punctuation">(</span>val<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">],</span> val<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">],</span> arr<span class="token punctuation">))
.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)[</span><span class="token number">0</span><span class="token punctuation">][</span><span class="token number">0</span><span class="token punctuation">];</span>
.</span><span class="token function">filter</span><span class="token punctuation">(([</span>i<span class="token punctuation">,</span> val<span class="token punctuation">])</span> <span class="token operator">=></span> <span class="token function">fn</span><span class="token punctuation">(</span>val<span class="token punctuation">,</span> i<span class="token punctuation">,</span> arr<span class="token punctuation">))
.</span><span class="token function">pop</span><span class="token punctuation">()[</span><span class="token number">0</span><span class="token punctuation">];</span>
</pre><label class="collapse">Show examples</label><pre class="language-js"><span class="token function">findLastIndex</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> n <span class="token operator">=></span> n <span class="token operator">%</span> <span class="token number">2</span> <span class="token operator">===</span> <span class="token number">1</span><span class="token punctuation">);</span> <span class="token comment">// 2 (index of the value 3)</span>
</pre><button class="primary clipboard-copy">&#128203;&nbsp;Copy to clipboard</button></div></div><div class="card fluid"><h3 id="flatten" class="section double-padded">flatten</h3><div class="section double-padded"><p>Flattens an array up to the specified depth.</p><p>Use recursion, decrementing <code>depth</code> by 1 for each level of depth. Use <code>Array.reduce()</code> and <code>Array.concat()</code> to merge elements or arrays. Base case, for <code>depth</code> equal to <code>1</code> stops recursion. Omit the second argument, <code>depth</code> to flatten only to a depth of <code>1</code> (single flatten).</p><pre class="language-js"><span class="token keyword">const</span> <span class="token function-variable function">flatten</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> depth <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">reduce</span><span class="token punctuation">((</span>a<span class="token punctuation">,</span> v<span class="token punctuation">)</span> <span class="token operator">=></span> a<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>depth <span class="token operator">></span> <span class="token number">1</span> <span class="token operator">&amp;&amp;</span> Array<span class="token punctuation">.</span><span class="token function">isArray</span><span class="token punctuation">(</span>v<span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token function">flatten</span><span class="token punctuation">(</span>v<span class="token punctuation">,</span> depth <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">) :</span> v<span class="token punctuation">), []);</span>