303 lines
8.3 KiB
JavaScript
303 lines
8.3 KiB
JavaScript
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const anagrams = str => {
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if(str.length <= 2) return str.length === 2 ? [str, str[1] + str[0]] : [str];
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return str.split('').reduce( (acc, letter, i) =>
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acc.concat(anagrams(str.slice(0, i) + str.slice(i + 1)).map( val => letter + val )), []);
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}
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// anagrams('abc') -> ['abc','acb','bac','bca','cab','cba']
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const average = arr =>
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arr.reduce( (acc , val) => acc + val, 0) / arr.length;
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// average([1,2,3]) -> 2
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const bottomVisible = _ =>
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document.documentElement.clientHeight + window.scrollY >= document.documentElement.scrollHeight || document.documentElement.clientHeight;
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// bottomVisible() -> true
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const capitalizeEveryWord = str => str.replace(/\b[a-z]/g, char => char.toUpperCase());
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// capitalizeEveryWord('hello world!') -> 'Hello World!'
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const capitalize = (str, lowerRest = false) =>
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str.slice(0, 1).toUpperCase() + (lowerRest? str.slice(1).toLowerCase() : str.slice(1));
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// capitalize('myName', true) -> 'Myname'
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const chainAsync = fns => { let curr = 0; const next = () => fns[curr++](next); next(); }
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/*
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chainAsync([
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next => { console.log('0 seconds'); setTimeout(next, 1000); },
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next => { console.log('1 second'); setTimeout(next, 1000); },
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next => { console.log('2 seconds'); }
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])
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*/
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const palindrome = str =>
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str.toLowerCase().replace(/[\W_]/g,'').split('').reverse().join('') === str.toLowerCase().replace(/[\W_]/g,'');
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// palindrome('taco cat') -> true
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const chunk = (arr, size) =>
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Array.apply(null, {length: Math.ceil(arr.length/size)}).map((v, i) => arr.slice(i*size, i*size+size));
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// chunk([1,2,3,4,5], 2) -> [[1,2],[3,4],5]
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const countOccurrences = (arr, value) => arr.reduce((a, v) => v === value ? a + 1 : a + 0, 0);
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// countOccurrences([1,1,2,1,2,3], 1) -> 3
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const currentUrl = _ => window.location.href;
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// currentUrl() -> 'https://google.com'
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const curry = (f, arity = f.length, next) =>
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(next = prevArgs =>
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nextArg => {
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const args = [ ...prevArgs, nextArg ];
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return args.length >= arity ? f(...args) : next(args);
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}
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)([]);
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// curry(Math.pow)(2)(10) -> 1024
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// curry(Math.min, 3)(10)(50)(2) -> 2
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const deepFlatten = arr =>
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arr.reduce( (a, v) => a.concat( Array.isArray(v) ? deepFlatten(v) : v ), []);
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// deepFlatten([1,[2],[[3],4],5]) -> [1,2,3,4,5]
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const difference = (arr, values) => arr.filter(v => !values.includes(v));
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// difference([1,2,3], [1,2]) -> [3]
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const distance = (x0, y0, x1, y1) => Math.hypot(x1 - x0, y1 - y0);
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// distance(1,1, 2,3) -> 2.23606797749979
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const isDivisible = (dividend, divisor) => dividend % divisor === 0;
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// isDivisible(6,3) -> true
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const escapeRegExp = str => str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
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// escapeRegExp('(test)') -> \\(test\\)
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const isEven = num => Math.abs(num) % 2 === 0;
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// isEven(3) -> false
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const factorial = n => n <= 1 ? 1 : n * factorial(n - 1);
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// factorial(6) -> 720
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const fibonacci = n =>
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Array(n).fill(0).reduce((acc, val, i) => acc.concat(i > 1 ? acc[i - 1] + acc[i - 2] : i),[]);
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// fibonacci(5) -> [0,1,1,2,3]
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const filterNonUnique = arr => arr.filter(i => arr.indexOf(i) === arr.lastIndexOf(i));
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// filterNonUnique([1,2,2,3,4,4,5]) -> [1,3,5]
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const flatten = arr => arr.reduce( (a, v) => a.concat(v), []);
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// flatten([1,[2],3,4]) -> [1,2,3,4]
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const arrayMax = arr => Math.max(...arr);
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// arrayMax([10, 1, 5]) -> 10
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const arrayMin = arr => Math.min(...arr);
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// arrayMin([10, 1, 5]) -> 1
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const getType = v =>
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v === undefined ? "undefined" : v === null ? "null" : v.constructor.name.toLowerCase();
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// getType(new Set([1,2,3])) -> "set"
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const getScrollPos = (el = window) =>
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( {x: (el.pageXOffset !== undefined) ? el.pageXOffset : el.scrollLeft,
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y: (el.pageYOffset !== undefined) ? el.pageYOffset : el.scrollTop} );
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// getScrollPos() -> {x: 0, y: 200}
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const gcd = (x , y) => !y ? x : gcd(y, x % y);
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// gcd (8, 36) -> 4
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const hammingDistance = (num1, num2) =>
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((num1^num2).toString(2).match(/1/g) || '').length;
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// hammingDistance(2,3) -> 1
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const head = arr => arr[0];
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// head([1,2,3]) -> 1
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const initial = arr => arr.slice(0,-1);
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// initial([1,2,3]) -> [1,2]
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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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// initializeArrayRange(5) -> [0,1,2,3,4]
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const initializeArray = (n, value = 0) => Array(n).fill(value);
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// initializeArray(5, 2) -> [2,2,2,2,2]
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const last = arr => arr.slice(-1)[0];
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// last([1,2,3]) -> 3
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const timeTaken = callback => {
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const t0 = performance.now(), r = callback();
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console.log(performance.now() - t0);
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return r;
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}
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// timeTaken(() => Math.pow(2, 10)) -> 1024 (0.010000000009313226 logged in console)
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const median = arr => {
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const mid = Math.floor(arr.length / 2), nums = arr.sort((a,b) => a - b);
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return arr.length % 2 !== 0 ? nums[mid] : (nums[mid - 1] + nums[mid]) / 2;
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}
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// median([5,6,50,1,-5]) -> 5
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// median([0,10,-2,7]) -> 3.5
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const objectFromPairs = arr => arr.reduce((a,v) => (a[v[0]] = v[1], a), {});
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// objectFromPairs([['a',1],['b',2]]) -> {a: 1, b: 2}
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const percentile = (arr, val) =>
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100 * arr.reduce((acc,v) => acc + (v < val ? 1 : 0) + (v === val ? 0.5 : 0), 0) / arr.length;
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// percentile([1,2,3,4,5,6,7,8,9,10], 6) -> 55
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const pipe = (...funcs) => arg => funcs.reduce((acc, func) => func(acc), arg);
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// pipe(btoa, x => x.toUpperCase())("Test") -> "VGVZDA=="
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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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// powerset([1,2]) -> [[], [1], [2], [2,1]]
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const promisify = func =>
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(...args) =>
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new Promise((resolve, reject) =>
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func(...args, (err, result) =>
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err ? reject(err) : resolve(result))
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);
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// const delay = promisify((d, cb) => setTimeout(cb, d))
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// delay(2000).then(() => console.log('Hi!')) -> Promise resolves after 2s
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const randomIntegerInRange = (min, max) => Math.floor(Math.random() * (max - min + 1)) + min;
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// randomIntegerInRange(0, 5) -> 2
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const randomInRange = (min, max) => Math.random() * (max - min) + min;
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// randomInRange(2,10) -> 6.0211363285087005
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const randomizeOrder = arr => arr.sort( (a,b) => Math.random() >= 0.5 ? -1 : 1);
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// randomizeOrder([1,2,3]) -> [1,3,2]
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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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// redirect('https://google.com')
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const reverseString = str => [...str].reverse().join('');
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// reverseString('foobar') -> 'raboof'
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const rgbToHex = (r, g, b) => ((r << 16) + (g << 8) + b).toString(16).padStart(6, '0');
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// rgbToHex(255, 165, 1) -> 'ffa501'
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const series = ps => ps.reduce((p, next) => p.then(next), Promise.resolve());
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// const delay = (d) => new Promise(r => setTimeout(r, d))
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// series([() => delay(1000), () => delay(2000)]) -> executes each promise sequentially, taking a total of 3 seconds to complete
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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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}
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}
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// scrollToTop()
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const shuffle = arr => {
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let r = arr.map(Math.random);
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return arr.sort((a,b) => r[a] - r[b]);
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}
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// shuffle([1,2,3]) -> [2, 1, 3]
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const similarity = (arr, values) => arr.filter(v => values.includes(v));
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// similarity([1,2,3], [1,2,4]) -> [1,2]
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const sortCharactersInString = str =>
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str.split('').sort( (a,b) => a.localeCompare(b) ).join('');
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// sortCharactersInString('cabbage') -> 'aabbceg'
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const sum = arr => arr.reduce( (acc , val) => acc + val, 0);
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// sum([1,2,3,4]) -> 10
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[varA, varB] = [varB, varA];
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// [x, y] = [y, x]
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const tail = arr => arr.length > 1 ? arr.slice(1) : arr;
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// tail([1,2,3]) -> [2,3]
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// tail([1]) -> [1]
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const truncate = (str, num) =>
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str.length > num ? str.slice(0, num > 3 ? num-3 : num) + '...' : str;
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// truncate('boomerang', 7) -> 'boom...'
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const unique = arr => [...new Set(arr)];
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// unique([1,2,2,3,4,4,5]) -> [1,2,3,4,5]
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const getUrlParameters = url =>
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url.match(/([^?=&]+)(=([^&]*))?/g).reduce(
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(a,v) => (a[v.slice(0,v.indexOf('='))] = v.slice(v.indexOf('=')+1), a), {}
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);
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// getUrlParameters('http://url.com/page?name=Adam&surname=Smith') -> {name: 'Adam', surname: 'Smith'}
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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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// uuid() -> '7982fcfe-5721-4632-bede-6000885be57d'
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const validateNumber = n => !isNaN(parseFloat(n)) && isFinite(n);
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// validateNumber('10') -> true
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const valueOrDefault = (value, d) => value || d;
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// valueOrDefault(NaN, 30) -> 30
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