Change all snippets from var to const
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@ -4,6 +4,6 @@ Convert each value to a hexadecimal string, using `toString(16)`, then `padStart
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Combine values using `join('')`.
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```js
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var rgbToHex = (r, g, b) =>
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const rgbToHex = (r, g, b) =>
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[r,g,b].map( v => v.toString(16).padStart(2,'0')).join('');
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```
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@ -5,6 +5,6 @@ Combine all key-value pairs into a single object using `Object.assign()` and the
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Pass `location.search` as the argument to apply to the current `url`.
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```js
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var getUrlParameters = url =>
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const getUrlParameters = url =>
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Object.assign(...url.match(/([^?=&]+)(=([^&]*))?/g).map(m => {[f,v] = m.split('='); return {[f]:v}}));
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```
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@ -3,7 +3,7 @@
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Use `crypto` API to generate a UUID, compliant with [RFC4122](https://www.ietf.org/rfc/rfc4122.txt) version 4.
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```js
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var uuid = _ =>
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const uuid = _ =>
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( [1e7]+-1e3+-4e3+-8e3+-1e11 ).replace( /[018]/g, c =>
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(c ^ crypto.getRandomValues(new Uint8Array(1))[0] & 15 >> c / 4).toString(16)
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)
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@ -6,7 +6,7 @@ Use `map()` to combine the letter with each partial anagram, then `reduce()` to
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Base cases are for string `length` equal to `2` or `1`.
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```js
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var anagrams = s => {
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const anagrams = s => {
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if(s.length <= 2) return s.length === 2 ? [s, s[1] + s[0]] : [s];
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return s.split('').reduce( (a,l,i) => {
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anagrams(s.slice(0,i) + s.slice(i+1)).map( v => a.push(l+v) );
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@ -3,6 +3,6 @@
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Use `reduce()` to add each value to an accumulator, initialized with a value of `0`, divide by the `length` of the array.
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```js
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var average = arr =>
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const average = arr =>
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arr.reduce( (acc , val) => acc + val, 0) / arr.length;
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```
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@ -3,5 +3,5 @@
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Use `slice(0,1)` and `toUpperCase()` to capitalize first letter, `slice(1)` to get the rest of the string.
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```js
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var capitalize = str => str.slice(0, 1).toUpperCase() + str.slice(1);
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const capitalize = str => str.slice(0, 1).toUpperCase() + str.slice(1);
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```
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@ -3,5 +3,5 @@
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Use `reduce()` to increment a counter each time you encounter the specific value inside the array.
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```js
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var countOccurrences = (arr, value) => arr.reduce((a, v) => v===value ? a + 1 : a + 0, 0);
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const countOccurrences = (arr, value) => arr.reduce((a, v) => v===value ? a + 1 : a + 0, 0);
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```
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@ -3,5 +3,5 @@
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Use `window.location.href` to get current URL.
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```js
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var currentUrl = _ => window.location.href;
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const currentUrl = _ => window.location.href;
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```
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@ -5,7 +5,7 @@ If the number of provided arguments (`args`) is sufficient, call the passed func
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Otherwise return a curried function `f` that expects the rest of the arguments.
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```js
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var curry = f =>
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const curry = f =>
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(...args) =>
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args.length >= f.length ? f(...args) : (...otherArgs) => curry(f)(...args, ...otherArgs)
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```
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@ -3,5 +3,5 @@
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Use `filter()` to remove values that are part of `values`, determined using `includes()`.
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```js
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var difference = (arr, values) => arr.filter(v => !values.includes(v));
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const difference = (arr, values) => arr.filter(v => !values.includes(v));
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```
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@ -3,7 +3,7 @@
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Use `replace()` to escape special characters.
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```js
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var escapeRegExp = s =>
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const escapeRegExp = s =>
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s.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
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}
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```
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@ -4,5 +4,5 @@ Use `Math.abs()` to extend logic to negative numbers, check using the modulo (`%
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Return `true` if the number is even, `false` if the number is odd.
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```js
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var isEven = num => Math.abs(num) % 2 === 0;
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const isEven = num => Math.abs(num) % 2 === 0;
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```
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@ -4,7 +4,7 @@ Create an empty array of the specific length, initializing the first two values
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Use `reduce()` to add values into the array, using the sum of the last two values, except for the first two.
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```js
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var fibonacci = n =>
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const fibonacci = n =>
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Array.apply(null, [0,1].concat(Array(n-2))).reduce(
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(acc, val, i) => {
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acc.push( i>1 ? acc[i-1]+acc[i-2] : val);
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@ -4,6 +4,6 @@ Use recursion.
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Use `reduce()` to get all elements that are not arrays, flatten each element that is an array.
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```js
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var flatten = arr =>
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const flatten = arr =>
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arr.reduce( (a, v) => a.concat( Array.isArray(v) ? flatten(v) : v ), []);
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```
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@ -5,5 +5,5 @@ Base case is when `y` equals `0`. In this case, return `x`.
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Otherwise, return the GCD of `y` and the remainder of the division `x/y`.
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```js
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var gcd = (x , y) => !y ? x : gcd(y, x % y);
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const gcd = (x , y) => !y ? x : gcd(y, x % y);
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```
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@ -3,5 +3,5 @@
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Return `arr[0]`.
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```js
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var head = arr => arr[0];
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const head = arr => arr[0];
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```
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@ -3,5 +3,5 @@
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Return `arr.slice(0,-1)`.
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```js
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var initial = arr => arr.slice(0,-1);
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const initial = arr => arr.slice(0,-1);
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```
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@ -4,6 +4,6 @@ Use `Array(end-start)` to create an array of the desired length, `map()` to fill
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You can omit `start` to use a default value of `0`.
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```js
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var initializeArrayRange = (end, start = 0) =>
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const initializeArrayRange = (end, start = 0) =>
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Array.apply(null, Array(end-start)).map( (v,i) => i + start );
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```
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@ -4,6 +4,6 @@ Use `Array(n)` to create an array of the desired length, `fill(v)` to fill it wi
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You can omit `v` to use a default value of `0`.
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```js
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var initializeArray = (n, v = 0) =>
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const initializeArray = (n, v = 0) =>
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Array(n).fill(v);
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```
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@ -3,5 +3,5 @@
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Return `arr.slice(-1)[0]`.
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```js
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var last = arr => arr.slice(-1)[0];
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const last = arr => arr.slice(-1)[0];
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```
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@ -4,7 +4,7 @@ Use `performance.now()` to get start and end time for the function, `console.log
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First argument is the function name, subsequent arguments are passed to the function.
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```js
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var timeTaken = (f,...args) => {
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const timeTaken = (f,...args) => {
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var t0 = performance.now(), r = f(...args);
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console.log(performance.now() - t0);
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return r;
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@ -3,6 +3,6 @@
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Use `map()` to create objects for each key-value pair, combine with `Object.assign()`.
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```js
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var objectFromPairs = arr =>
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const objectFromPairs = arr =>
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Object.assign(...arr.map( v => {return {[v[0]] : v[1]};} ));
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```
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@ -1,8 +1,8 @@
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### Powerset
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Use `reduce()` combined with `map()` to iterate over elements and combine into an array containing all combinations.
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Use `reduce()` combined with `map()` to iterate over elements and combine into an array containing all combinations.
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```js
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var powerset = arr =>
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const powerset = arr =>
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arr.reduce( (a,v) => a.concat(a.map( r => [v].concat(r) )), [[]]);
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```
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@ -3,5 +3,5 @@
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Use `Math.random()` to generate a random value, map it to the desired range using multiplication.
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```js
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var randomInRange = (min, max) => Math.random() * (max - min) + min;
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const randomInRange = (min, max) => Math.random() * (max - min) + min;
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```
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@ -3,5 +3,5 @@
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Use `sort()` to reorder elements, utilizing `Math.random()` to randomize the sorting.
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```js
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var randomizeOrder = arr => arr.sort( (a,b) => Math.random() >= 0.5 ? -1 : 1)
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const randomizeOrder = arr => arr.sort( (a,b) => Math.random() >= 0.5 ? -1 : 1)
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```
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@ -4,6 +4,6 @@ Use `window.location.href` or `window.location.replace()` to redirect to `url`.
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Pass a second argument to simulate a link click (`true` - default) or an HTTP redirect (`false`).
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```js
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var redirect = (url, asLink = true) =>
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const redirect = (url, asLink = true) =>
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asLink ? window.location.href = url : window.location.replace(url);
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```
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@ -4,5 +4,5 @@ Use array destructuring and `Array.reverse()` to reverse the order of the charac
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Combine characters to get a string using `join('')`.
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```js
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var reverseString = str => [...str].reverse().join('');
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const reverseString = str => [...str].reverse().join('');
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```
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@ -4,8 +4,8 @@ Get distance from top using `document.documentElement.scrollTop` or `document.bo
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Scroll by a fraction of the distance from top. Use `window.requestAnimationFrame()` to animate the scrolling.
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```js
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var scrollToTop = _ => {
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var c = document.documentElement.scrollTop || document.body.scrollTop;
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const scrollToTop = _ => {
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const c = document.documentElement.scrollTop || document.body.scrollTop;
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if(c > 0) {
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window.requestAnimationFrame(scrollToTop);
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window.scrollTo(0, c - c/8);
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@ -3,5 +3,5 @@
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Use `filter()` to remove values that are not part of `values`, determined using `includes()`.
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```js
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var difference = (arr, values) => arr.filter(v => values.includes(v));
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const difference = (arr, values) => arr.filter(v => values.includes(v));
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```
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@ -3,6 +3,6 @@
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Split the string using `split('')`, `sort()` utilizing `localeCompare()`, recombine using `join('')`.
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```js
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var sortCharactersInString = str =>
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const sortCharactersInString = str =>
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str.split('').sort( (a,b) => a.localeCompare(b) ).join('');
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```
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@ -3,6 +3,6 @@
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Use `reduce()` to add each value to an accumulator, initialized with a value of `0`.
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```js
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var sum = arr =>
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const sum = arr =>
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arr.reduce( (acc , val) => acc + val, 0);
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```
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@ -3,5 +3,5 @@
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Return `arr.slice(1)`.
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```js
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var tail = arr => arr.slice(1);
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const tail = arr => arr.slice(1);
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```
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@ -4,5 +4,5 @@ Use `!isNaN` in combination with `parseFloat()` to check if the argument is a nu
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Use `isFinite()` to check if the number is finite.
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```js
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var validateNumber = n => !isNaN(parseFloat(n)) && isFinite(n);
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const validateNumber = n => !isNaN(parseFloat(n)) && isFinite(n);
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```
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