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

Build

Browse Source
This commit is contained in:
Angelos Chalaris
2017-12-20 13:01:51 +02:00
parent 95dd408735
commit 8feecd6e20
1 changed files with 5 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
docs/index.html
View File

@ -331,7 +331,7 @@ Use <code>Array.reduce()</code> to create an object, where the keys are produced
<p>Initializes an array containing the numbers in the specified range where <code>start</code> and <code>end</code> are inclusive.</p>
<p>Use <code>Array((end + 1) - start)</code> to create an array of the desired length, <code>Array.map()</code> to fill with the desired values in a range.
You can omit <code>start</code> to use a default value of <code>0</code>.</p>
<pre><code class="language-js">const initializeArrayWithRange = (end, start = 0) =&gt;
<pre><code class="language-js">const initializeArrayWithRange = (end, start = 0) =&gt;
Array.from({ length: (end + 1) - start }).map((v, i) =&gt; i + start);
// initializeArrayWithRange(5) -&gt; [0,1,2,3,4,5]
// initializeArrayWithRange(7, 3) -&gt; [3,4,5,6,7]
@ -358,7 +358,7 @@ You can omit <code>value</code> to use a default value of <code>0</code>.</p>
</div></div><br/><div class="card fluid"><div class="section double-padded"><h3 id="mapobject">mapObject</h3></div><div class="section double-padded">
<p>Maps the values of an array to an object using a function, where the key-value pairs consist of the original value as the key and the mapped value.</p>
<p>Use an anonymous inner function scope to declare an undefined memory space, using closures to store a return value. Use a new <code>Array</code> to stor the array with a map of the function over its data set and a comma operator to return a second step, without needing to move from one context to another (due to closures and order of operations).</p>
<pre><code class="language-js">const mapObject = (arr, fn) =&gt;
<pre><code class="language-js">const mapObject = (arr, fn) =&gt;
(a =&gt; (a = [arr, arr.map(fn)], a[0].reduce( (acc,val,ind) =&gt; (acc[val] = a[1][ind], acc), {}) )) ( );
/*
const squareIt = arr =&gt; mapObject(arr, a =&gt; a*a)
@ -408,7 +408,7 @@ Use <code>Array.push()</code> to keep track of pulled values</p>
let removed = [];
let pulled = arr.map((v, i) =&gt; pullArr.includes(i) ? removed.push(v) : v)
.filter((v, i) =&gt; !pullArr.includes(i))
arr.length = 0;
arr.length = 0;
pulled.forEach(v =&gt; arr.push(v));
return removed;
}
@ -425,7 +425,7 @@ Use <code>Array.push()</code> to keep track of pulled values</p>
Use <code>Array.length = 0</code> to mutate the passed in array by resetting it's length to zero and <code>Array.push()</code> to re-populate it with only the pulled values.
Use <code>Array.push()</code> to keep track of pulled values</p>
<pre><code class="language-js">const pullAtValue = (arr, pullArr) =&gt; {
let removed = [],
let removed = [],
pushToRemove = arr.forEach((v, i) =&gt; pullArr.includes(v) ? removed.push(v) : v),
mutateTo = arr.filter((v, i) =&gt; !pullArr.includes(v));
arr.length = 0;
@ -787,7 +787,7 @@ Count and return the number of <code>1</code>s in the string, using <code>match(
</div></div><br/><div class="card fluid"><div class="section double-padded"><h3 id="isarmstrongnumber">isArmstrongNumber</h3></div><div class="section double-padded">
<p>Checks if the given number is an armstrong number or not.</p>
<p>Convert the given number into array of digits. Use <code>Math.pow()</code> to get the appropriate power for each digit and sum them up. If the sum is equal to the number itself, return <code>true</code> otherwise <code>false</code>.</p>
<pre><code class="language-js">const isArmstrongNumber = digits =&gt;
<pre><code class="language-js">const isArmstrongNumber = digits =&gt;
( arr =&gt; arr.reduce( ( a, d ) =&gt; a + Math.pow( parseInt( d ), arr.length ), 0 ) == digits ? true : false )( ( digits+'' ).split( '' ) );
// isArmstrongNumber(1634) -&gt; true
// isArmstrongNumber(371) -&gt; true