Travis build: 1043

README.md

@@ -676,7 +676,7 @@ const sum = pipeAsyncFunctions(
   x => x + 3,
   async x => (await x) + 4
 );
-(async() => {
+(async () => {
   console.log(await sum(5)); // 15 (after one second)
 })();
 ```
@@ -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([2.1, 1.2], [2.3, 3.4], Math.floor); // [1]
-differenceBy([{ x: 2 }, { x: 1 }], [{ x: 1 }], v => v.x); // [ { x: 2 } ]
+differenceBy([{ x: 2 }, { x: 1 }], [{ x: 1 }], v => v.x); // [2]
 ```
 
 </details>
@@ -2321,9 +2321,9 @@ The `func` is invoked with three arguments (`value, index, array`).
 const remove = (arr, func) =>
   Array.isArray(arr)
     ? arr.filter(func).reduce((acc, val) => {
-      arr.splice(arr.indexOf(val), 1);
+        arr.splice(arr.indexOf(val), 1);
-      return acc.concat(val);
+        return acc.concat(val);
-    }, [])
+      }, [])
     : [];
 ```
 
@@ -5504,8 +5504,8 @@ Throws an exception if `n` is a negative number.
 const factorial = n =>
   n < 0
     ? (() => {
-      throw new TypeError('Negative numbers are not allowed!');
+        throw new TypeError('Negative numbers are not allowed!');
-    })()
+      })()
     : n <= 1
       ? 1
       : n * factorial(n - 1);

docs/adapter.html

@@ -133,7 +133,7 @@ Object<span class="token punctuation">.</span><span class="token function">assig
   x <span class="token operator">=></span> x <span class="token operator">+</span> <span class="token number">3</span><span class="token punctuation">,</span>
   <span class="token keyword">async</span> x <span class="token operator">=></span> <span class="token punctuation">(</span><span class="token keyword">await</span> x<span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token number">4</span>
 <span class="token punctuation">);
-(</span><span class="token keyword">async</span><span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
+(</span><span class="token keyword">async</span> <span class="token punctuation">()</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
   console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token keyword">await</span> <span class="token function">sum</span><span class="token punctuation">(</span><span class="token number">5</span><span class="token punctuation">));</span> <span class="token comment">// 15 (after one second)</span>
 <span class="token punctuation">})();</span>
 </pre></div><div class="card code-card"><div class="section card-content"><h4><a href="https://frontendmasters.com/courses/es6-right-parts/" target="_blank" rel="noopener noreferrer">Recommended Resource - ES6: The Right Parts</a></h4><p>Learn new ES6 JavaScript language features like arrow function, destructuring, generators & more to write cleaner and more productive, readable programs.</p></div></div><div class="card code-card"><div class="corner intermediate"></div><div class="section card-content"><h4 id="pipefunctions">pipeFunctions</h4><p>Performs left-to-right function composition.</p><p>Use <code>Array.prototype.reduce()</code> with the spread operator (<code>...</code>) to perform left-to-right function composition. The first (leftmost) function can accept one or more arguments; the remaining functions must be unary.</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">pipeFunctions</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">...</span>fns<span class="token punctuation">)</span> <span class="token operator">=></span> fns<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">((</span>f<span class="token punctuation">,</span> g<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token function">g</span><span class="token punctuation">(</span><span class="token function">f</span><span class="token punctuation">(</span><span class="token operator">...</span>args<span class="token punctuation">)));</span>

docs/index.html

@@ -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>
+</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">// [ { x: 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">// [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>
@@ -410,9 +410,9 @@
 </pre></div><div class="card code-card"><div class="corner intermediate"></div><div class="section card-content"><h4 id="remove">remove</h4><p>Removes elements from an array for which the given function returns <code>false</code>.</p><p>Use <code>Array.prototype.filter()</code> to find array elements that return truthy values and <code>Array.prototype.reduce()</code> to remove elements using <code>Array.prototype.splice()</code>. The <code>func</code> is invoked with three arguments (<code>value, index, array</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">remove</span> <span class="token operator">=</span> <span class="token punctuation">(</span>arr<span class="token punctuation">,</span> func<span class="token punctuation">)</span> <span class="token operator">=></span>
   Array<span class="token punctuation">.</span><span class="token function">isArray</span><span class="token punctuation">(</span>arr<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>func<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> <span class="token punctuation">{</span>
-      arr<span class="token punctuation">.</span><span class="token function">splice</span><span class="token punctuation">(</span>arr<span class="token punctuation">.</span><span class="token function">indexOf</span><span class="token punctuation">(</span>val<span class="token punctuation">),</span> <span class="token number">1</span><span class="token punctuation">);</span>
+        arr<span class="token punctuation">.</span><span class="token function">splice</span><span class="token punctuation">(</span>arr<span class="token punctuation">.</span><span class="token function">indexOf</span><span class="token punctuation">(</span>val<span class="token punctuation">),</span> <span class="token number">1</span><span class="token punctuation">);</span>
-      <span class="token keyword">return</span> acc<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>val<span class="token punctuation">);
+        <span class="token keyword">return</span> acc<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>val<span class="token punctuation">);
-    }, [])
+      }, [])
     : [];</span>
 </pre><label class="collapse">examples</label><pre class="section card-examples language-js"><span class="token function">remove</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">0</span><span class="token punctuation">);</span> <span class="token comment">// [2, 4]</span>
 </pre></div><div class="card code-card"><div class="corner beginner"></div><div class="section card-content"><h4 id="sample">sample</h4><p>Returns a random element from an array.</p><p>Use <code>Math.random()</code> to generate a random number, multiply it by <code>length</code> and round it off to the nearest whole number using <code>Math.floor()</code>. This method also works with strings.</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">sample</span> <span class="token operator">=</span> arr <span class="token operator">=></span> arr<span class="token punctuation">[</span>Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span><span class="token function">random</span><span class="token punctuation">()</span> <span class="token operator">*</span> arr<span class="token punctuation">.</span>length<span class="token punctuation">)];</span>

docs/math.html

@@ -152,8 +152,8 @@ own individual rating by supplying it as the third argument.
 </pre></div><div class="card code-card"><div class="corner beginner"></div><div class="section card-content"><h4 id="factorial">factorial</h4><p>Calculates the factorial of a number.</p><p>Use recursion. If <code>n</code> is less than or equal to <code>1</code>, return <code>1</code>. Otherwise, return the product of <code>n</code> and the factorial of <code>n - 1</code>. Throws an exception if <code>n</code> is a negative number.</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">factorial</span> <span class="token operator">=</span> n <span class="token operator">=></span>
   n <span class="token operator">&lt;</span> <span class="token number">0</span>
     <span class="token operator">?</span> <span class="token punctuation">(()</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
-      <span class="token keyword">throw new</span> <span class="token class-name">TypeError</span><span class="token punctuation">(</span><span class="token string">'Negative numbers are not allowed!'</span><span class="token punctuation">);
+        <span class="token keyword">throw new</span> <span class="token class-name">TypeError</span><span class="token punctuation">(</span><span class="token string">'Negative numbers are not allowed!'</span><span class="token punctuation">);
-    })()
+      })()
     :</span> n <span class="token operator">&lt;=</span> <span class="token number">1</span>
       <span class="token operator">?</span> <span class="token number">1</span>
       <span class="token punctuation">:</span> n <span class="token operator">*</span> <span class="token function">factorial</span><span class="token punctuation">(</span>n <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">);</span>

snippets/factorial.md

@@ -11,8 +11,8 @@ Throws an exception if `n` is a negative number.
 const factorial = n =>
   n < 0
     ? (() => {
-      throw new TypeError('Negative numbers are not allowed!');
+        throw new TypeError('Negative numbers are not allowed!');
-    })()
+      })()
     : n <= 1
       ? 1
       : n * factorial(n - 1);

snippets/pipeAsyncFunctions.md

@@ -17,7 +17,7 @@ const sum = pipeAsyncFunctions(
   x => x + 3,
   async x => (await x) + 4
 );
-(async() => {
+(async () => {
   console.log(await sum(5)); // 15 (after one second)
 })();
 ```

snippets/remove.md

@@ -9,9 +9,9 @@ The `func` is invoked with three arguments (`value, index, array`).
 const remove = (arr, func) =>
   Array.isArray(arr)
     ? arr.filter(func).reduce((acc, val) => {
-      arr.splice(arr.indexOf(val), 1);
+        arr.splice(arr.indexOf(val), 1);
-      return acc.concat(val);
+        return acc.concat(val);
-    }, [])
+      }, [])
     : [];
 ```
 

test/_30s.js

@@ -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) =>
@@ -341,8 +341,8 @@ const extendHex = shortHex =>
 const factorial = n =>
   n < 0
     ? (() => {
-      throw new TypeError('Negative numbers are not allowed!');
+        throw new TypeError('Negative numbers are not allowed!');
-    })()
+      })()
     : n <= 1
       ? 1
       : n * factorial(n - 1);
@@ -990,9 +990,9 @@ const reject = (pred, array) => array.filter((...args) => !pred(...args));
 const remove = (arr, func) =>
   Array.isArray(arr)
     ? arr.filter(func).reduce((acc, val) => {
-      arr.splice(arr.indexOf(val), 1);
+        arr.splice(arr.indexOf(val), 1);
-      return acc.concat(val);
+        return acc.concat(val);
-    }, [])
+      }, [])
     : [];
 const removeNonASCII = str => str.replace(/[^\x20-\x7E]/g, '');
 const renameKeys = (keysMap, obj) =>