整點簡單的，分享10個數(shù)組工具類

1.數(shù)組并集

const union = function (a, b, k) {
    return a.concat(b.filter(i => (k ? !a.map(i => i[k]).includes(i[k]) : !a.includes(i))))
}
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示例：

let a = [1, 2, 3, 4, 5]
let b = [1, 2, 4, 5, 6]
union(a, b) //[1,2,3,4,5,6]

// 場景2：
let a1 = [
    { id: 1, name: '張三', age: 20 },
    { id: 2, name: '李四', age: 21 },
    { id: 3, name: '小二', age: 23 }
]
let b1 = [
    { id: 2, name: '李四', age: 21 },
    { id: 4, name: '小明', age: 24 },
    { id: 5, name: '小紅', age: 25 }
]

// 通過 id 獲取并集
union(a1, b1, 'id')
/*
[
  {id: 1, name: "張三", age: 20}
  {id: 2, name: "李四", age: 21}
  {id: 3, name: "小二", age: 23}
  {id: 4, name: "小明", age: 24}
  {id: 5, name: "小紅", age: 25}
]
*/
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2.數(shù)組交集

const intersection = function (a, b, k) {
    return a.filter(t => (k ? b.map(i => i[k]).includes(t[k]) : b.includes(t)))
}
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示例：

let a = [1, 2, 3, 4, 5]
let b = [1, 2, 4, 5, 6]
intersection(a, b) // [1,2,4,5]

// 場景2：
let a1 = [
    { id: 1, name: '張三', age: 20 },
    { id: 2, name: '李四', age: 21 },
    { id: 3, name: '小二', age: 23 }
]
let b1 = [
    { id: 2, name: '李四', age: 21 },
    { id: 4, name: '小明', age: 24 },
    { id: 5, name: '小紅', age: 25 }
]
intersection(a1, b1, 'id') //[ { id: 2, name: '李四', age: 21 }]
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3.數(shù)組差集

const except = function (a, b, k) {
    return [...a, ...b].filter(i => ![a, b].every(t => (k ? t.map(i => i[k]).includes(i[k]) : t.includes(i))))
}
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示例：

let a = [1, 2, 3, 4, 5]
let b = [1, 2, 4, 5, 6]

except(a, b) // [3,6]

let a1 = [
    { id: 1, name: '張三', age: 20 },
    { id: 2, name: '李四', age: 21 },
    { id: 3, name: '小二', age: 23 }
]
let b1 = [
    { id: 2, name: '李四', age: 21 },
    { id: 4, name: '小明', age: 24 },
    { id: 5, name: '小紅', age: 25 }
]


except(a1, b1, 'id')
/*
[
  {id: 1, name: "張三", age: 20}
  {id: 3, name: "小二", age: 23}
  {id: 4, name: "小明", age: 24}
  {id: 5, name: "小紅", age: 25}
]
*/
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4.數(shù)組分組

/**
 * @description: 一維數(shù)組轉二維數(shù)組 (分組)
 * @param {Array} arr:數(shù)組
 * @param {Number} num: 平分基數(shù)（num 個為一組進行分組（歸檔））
 */
const group = function (arr, num) {
    return [...Array(Math.ceil(arr.length / num)).keys()].reduce((p, _, i) => (p.push(arr.slice(i * num, (i + 1) * num)), p), [])
}
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示例：

  group([1,2,3,4,5,6,7,8,9,10],2) // [[1,2],[3,4],[5,6],[7,8],[9.10]]
 
  group([1,2,3,4,5,6,7,8,9,10],3) // [[1,2,3],[4,5,6],[7,8,9],[10]]
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5.數(shù)組平均數(shù)

/**
 * 數(shù)組平均數(shù)
 * @param {Array} a:數(shù)組
 * @param {Function | String} f:函數(shù) 或 key
 */
const mean = function (a, f) {
    return (f ? a.map(typeof f === 'function' ? f : v => v[f]) : a).reduce((acc, val) => acc + val * 1, 0) / a.length
}
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示例：

  mean([{ n: 4 }, { n: 2 }, { n: 8 }, { n: 6 }], o => o.n) // 5
  mean([{ n: 4 }, { n: 2 }, { n: 8 }, { n: 6 }], 'n') // 5
  mean([4, 2, 8, 6]) // 5
  mean(['4', 2, '8', 6]) // 5
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6.數(shù)組生成

/**
 * @description: 生成 起止數(shù)字間（包含起止數(shù)字）的升序數(shù)組
 * @param {Number} min : 最小值
 * @param {Number} max ：最大值
 */
const range = function (min, max) {
    return Array.from({ length: max - min + 1 }, (_, i) => i + min)
}
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示例：

 range(0,10) // [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
 range(1,9)  // [1, 2, 3, 4, 5, 6, 7, 8, 9]
 
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7.數(shù)組求和

const sum = function (a, k) {
    return a.reduce((p, c) => p + (k ? c[k] || 0 : c), 0)
}
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示例：

let a = [1, 2, 3, 4, 5]
sum(a) // 15

let a1 = [
    { id: 1, name: '張三', age: 20 },
    { id: 2, name: '李四', age: 21 },
    { id: 3, name: '小二', age: 23 }
]
sum(a1, 'age') // 64 
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8.數(shù)組扁平化

/**
 * 指定深度扁平化數(shù)組
 * @param {Array} arr :扁平化的數(shù)組
 * @param {Number} depth：扁平化的層級
 */
const flatten = function (arr, depth = 1) {
    return arr.reduce((a, v) => a.concat(depth > 1 && Array.isArray(v) ? flatten(v, depth - 1) : v), [])
}
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示例：

 flatten([1, 2, 3, [4, [5, 6, [7]]]]) //[1, 2, 3, 4, [5,6,[7]]]
 
 flatten([1, 2, 3, [4, [5, 6, [7]]]], 2) //[1, 2, 3, 4, 5,6,[7]]
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9. 數(shù)組值位置交換

/**
 * @description: 交換數(shù)組中任一兩個值的位置
 * @param {Array} arr:數(shù)組
 * @param {Number} oldIndex：老位置索引
 * @param {Number} newIndex：新位置索引
 * @param {Boolean} isChangeOldArr: 是否改變原數(shù)組
 * @return {Array} 返回一個數(shù)組
 */
const exchangePostion = function (arr, oldIndex, newIndex, isChangeOldArr = false) {
    let a = isChangeOldArr ? arr : JSON.parse(JSON.stringify(arr))
    a.splice(oldIndex, 1, a.splice(newIndex, 1, a[oldIndex])[0])
    return a
}
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示例：

 let a1 = [1, 2, 3, 4, 5, 6]
 
 exchangePostion(a1, 4, 1)// [1, 5, 3, 4, 2, 6]
 
 a1 //[1, 2, 3, 4, 5, 6]
 
 let a1 = [1, 2, 3, 4, 5, 6]
 
 exchangePostion(a1, 4, 1，true)// [1, 5, 3, 4, 2, 6]
 
  a1 // [1, 5, 3, 4, 2, 6]
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10.數(shù)組歸檔

/**
 * @description: 對一維 json 數(shù)組進行歸檔（根據(jù) key）
 * @param {Array} arr:一維數(shù)組
 * @param {String} key：key 字符串
 */
const archive = function (arr, key) {
    return Array.from(new Set(arr.map(i => i[key]))).reduce((p, c) => (p.push(arr.filter(i => i[key] === c)), p), [])
}
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示例：

let books = [ {date:'1月',name:'地理書'}, {date:'1月',name:'歷史書'}, {date:'2月',name:'化學書'} ]

archive( books, 'date') 
// [[{date:'1月',name:'地理書'},{date:'1月',name:'歷史書'}],[ {date:'2月',name:'化學書'}]]
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轉自：https://juejin.cn/post/6975846295059562503