小馬過河﹎

摘要： JavaScript const sample = arr => arr[Math.floor(Math.random() * arr.length)] Examples sample([3, 7, 9, 11]) // 9 阅读全文

摘要： JavaScript const avg = (...nums) => nums.reduce((acc, val) => acc + val, 0) / nums.length Examples avg(...[1, 2, 3]) // 2 avg(1, 2, 3) // 2 阅读全文

摘要： 过滤掉虚假值：false, null, 0, "", undefined, NaN JavaScript const compact = arr => arr.filter(Boolean) Examples compact([0, 1, false, 2, '', 3, 'a', 'e' * 23 阅读全文

摘要： JavaScript const sum = (...arr) => [...arr].reduce((acc, val) => acc + val, 0) Examples sum(1, 2, 3, 4) // 10 sum(...[1, 2, 3, 4]) // 10 阅读全文

摘要： JavaScript const countOccurrences = (arr, val) => arr.reduce((a, v) => (v val ? a + 1 : a), 0) Examples countOccurrences([1, 1, 2, 1, 2, 3], 1) // 3 阅读全文

摘要： JavaScript const intersection = (a, b) => { const s = new Set(b) return [...new Set(a)].filter(x => s.has(x)) } Examples intersection([1, 2, 3], [4, 3 阅读全文

摘要： JavaScript const nthElement = (arr, n = 0) => (n -1 ? arr.slice(n) : arr.slice(n, n + 1))[0] Examples nthElement(['a', 'b', 'c'], 1) // 'b' nthElement 阅读全文

摘要： JavaScript const without = (arr, ...args) => arr.filter(v => !args.includes(v)) Examples without([2, 1, 2, 3], 1, 2) // [3] 阅读全文

摘要： JavaScript const firstN = (arr, n) => arr.slice(0, n) Examples firstN(['a', 'b', 'c', 'd'], 2) // ['a', 'b'] 阅读全文

摘要： JavaScript const lastN = (arr, n) => arr.slice(-n) Examples lastN(['a', 'b', 'c', 'd'], 2) // ['c', 'd'] 阅读全文

摘要： JavaScript const uniqueElements = arr => [...new Set(arr)] Examples uniqueElements([1, 2, 2, 3, 4, 4, 5]) // [1, 2, 3, 4, 5] 阅读全文

摘要： JavaScript const hasDuplicates = arr => new Set(arr).size !== arr.length Examples hasDuplicates([0, 1, 1, 2]) // true hasDuplicates([0, 1, 2, 3]) // f 阅读全文

摘要： JavaScript const castArray = val => (Array.isArray(val) ? val : [val]) Examples castArray('foo') // ['foo'] castArray([1]) // [1] 阅读全文

摘要： JavaScript const includesAll = (big, small) => small.every(s => big.includes(s)) Examples includesAll([1, 2, 3, 4], [1, 4]) // true includesAll([1, 2, 阅读全文

摘要： JavaScript const includesAny = (arr1, arr2) => arr2.some(i2 => arr1.includes(i2)) Examples includesAny([1, 2, 3, 4], [2, 9]) // true includesAny([1, 2 阅读全文

摘要： JavaScript const union = (a, b) => Array.from(new Set([...a, ...b])) Examples union([1, 2, 3], [4, 3, 2]) // [1, 2, 3, 4] 阅读全文

摘要： loops 循环 const files = ['foo.txt ', '.bar', ' ', 'baz.foo'] let filePaths = [] for (let file of files) { const fileName = file.trim() if (fileName) { 阅读全文