Lodash經常使用用法總結

時間 2019-11-16

標籤 lodash 經常使用用法總結简体版

原文原文鏈接

Lodash是一個輕量級的JavaScript工具函數庫，它方便了平常開發中對數據的操做，提升了開發效率。

平常開發中，一般會對數據，特別是數組和對象進行各類讀寫等操做：好比去重，拷貝，合併，過濾，求交集，求和等等。根據平時開發中對數據的操做，我對Lodash常見的用法作了如下總結，方便從此的學習和整理。javascript

Array

Create

建立一個數組，元素爲0, 1, 2, ... , 23java

_.range([start=0], end, [step=1])
```
let arr = _.range(24)

console.log(arr) // [0, 1, 2, 3, ... , 23]
```
建立一個數組，元素爲100, 100, 100, 100, 100數組

_.fill(array, value, [start=0], [end=array.length])
```
let arr = _.fill(Array(5), 100)

console.log(arr) // [100, 100, 100, 100, 100]
```

Read

獲取數組中最後一個元素dom

_.last(array)

let arr = [1, 2, 3, 4, 5]
let lastElement = _.last(arr) 

console.log(lastElement) // 5

獲取數組中倒數第二個元素ide

_.nth(array, [n=0])

let arr = [1, 2, 3, 4, 5]
let lastSecondElement = _.nth(-2) 

console.log(lastSecondElement) // 4

獲取對象數組中某一同名屬性的屬性值集合函數

_.map(collection, [iteratee=_.identity])

let users = [{
      id: 12,
      name: 'Adam',
      hobbies: [
        {name: 'running', index: 100},
        {name: 'cycling', index: 95}
      ]
   },{
      id: 14,
      name: 'Bob',
      hobbies: [
        {name: 'movie', index: 98},
        {name: 'music', index: 85}
      ]
   },{
      id: 16,
      name: 'Charlie',
      hobbies: [
       {name: 'travelling', index: 90},
       {name: 'fishing', index: 88}
      ]
   },{
      id: 18,
      name: 'David',
      hobbies: [
       {name: 'walking', index: 99},
       {name: 'football', index: 85}
     ]                


   }
]
let userIds = _.map(users, 'id')
let mostFavouriteHobbies = _.map(users, 'hobbies[0].name')

console.log(userIds) // [12, 14, 16, 18]
console.log(mostFavouriteHobbies) // ["running", "movie", "travelling", "walking"]

獲取對象數組中某一屬性值最大的對象工具

_.maxBy(array, [iteratee=_.identity])

let arr = [{a:1, b: 2, c: {d:4}}, {a:3, b: 4, c: {d:6}}]
let maxBObj = _.maxBy(arr, 'b')

console.log(maxBObj) // {a: 3, b: 4, c: {d: 6}}

找出兩個數組中元素值相同的元素學習

_.intersection([arrays])

let arr1 = [2, 1, {a: 1, b: 2}]
let arr2 = [2, 3, {a: 1, b: 2}]
let intersection = _.intersection(arr1, arr2) 

console.log(intersection) // [2]

求數值數組中元素值的平均數spa

_.mean(array)

let numbers = [1, 2, 3, 4, 5]
let average = _.mean(numbers)

console.log(average) // 3

求對象數組中某個屬性值的平均數code

_.meanBy(array, [iteratee=_.identity])

let objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }]
let average = _.meanBy(objects, 'n')

console.log(average) // 5

獲取數組中前n個元素，不改變原數組

_.take(array, [n=1])

let arr = [1, 2, 3, 4, 5]
let part1Arr = _.take(arr, 4)
let part2Arr = _.take(arr, 6)
let part3Arr = _.take([], 5)

console.log(part1Arr) // [1, 2, 3, 4]
console.log(part2Arr) // [1, 2, 3, 4, 5]
console.log(part3Arr) // []

Delete

刪除數組中值爲falsy的元素

_.compact(array)

let arr = [0, 1, false, 2, '', 3, null, undefined, NaN]
let truthyArr = _.compact(arr) 

console.log(truthyArr) // [1, 2, 3]

Format

去重。

_.uniq(array)

let arr = [2, 1, 2, '2', true]
let uniqArr = _.uniq(arr)

console.log(uniqArr) // [2, 1, '2', true]

排序。對象數組，根據對象中的某個屬性的值，升序或降序排序

_.orderBy(collection, [iteratees=[_.identity]], [orders])

let users = [
  {user: 'Tom', age: 25},
  {user: 'Amy', age: 23},
  {user: 'Perter', age: 22},
  {user: 'Ben', age: 29}
]
let sortedUsers = _.orderBy(users, 'age', 'desc')

console.log(sortedUsers)
// [{user: "Ben", age: 29}, {user: "Tom", age: 25}, {user: "Amy", age: 23}, {user: "Perter", age: 22}]

分割數組[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]爲 [1, 2, 3, 4, 5] 和 [6, 7, 8, 9, 10]

_.chunk(array, [size=1])

let arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
let [left, right] = _.chunk(arr, 5)

console.log(left) // [1, 2, 3, 4, 5]
console.log(right) // [6, 7, 8, 9, 10]

脫掉一層[]

_.flatten(array)

let address = {
  '江蘇省': ['南京市', '蘇州市'],
  '浙江省': ['杭州市', '紹興市']
}
let cities = _.flatten(_.values(address))

console.log(cities) // ["南京市", "蘇州市", "杭州市", "紹興市"]

將多維數組轉爲一維數組

_.flattenDeep(array)

let flattenedArr = _.flattenDeep([1, [2, [3, [4]], 5]]);

console.log(flattenedArr) // [1, 2, 3, 4, 5]

Object

Create

經過數組["x", "y"] 和數組[10, 10] 建立對象 {x: 10, y: 10}

_.zipObject([props=[]], [values=[]])

let keys = ["x", "y"]
let values = [10, 10]
let obj = _.zipObject(keys, values) 

console.log(obj) // {x: 10, y: 10}

合併對象

_.assign(object, [sources])

let desObj = {name: '', gender: 'male', job: 'developer'}
let sourceObj = {name: 'Tom', job: ''}
let mergedObj = _.assign(desObj, sourceObj)

console.log(mergedObj) // {name: "Tom", gender: "male", job: ""}

深拷貝對象

_.cloneDeep(value)

let sourceObj = {department_id: 1, permissions: {management: [1, 2, 3, 4], store: [11, 12, 13, 14]}}
let desObj = _.cloneDeep(sourceObj)
desObj.permissions.store.push(15, 16)

console.log(desObj)
// {department_id: 1, permissions: {management: [1, 2, 3, 4], store: [11, 12, 13, 14, 15, 16]}}
console.log(sourceObj)
// {department_id: 1, permissions: {management: [1, 2, 3, 4], store: [11, 12, 13, 14]}}

合併多個對象中key值相同的鍵值對

_.merge(object, [sources])

let obj1 = {'9': {name: '樂購超市'}}
let obj2 = {'9': {storeToken: 'xxx'}}
let obj3 = {'9': {storePosition: 'Hangzhou'}}
let mergedObj = _.merge(obj1, obj2, obj3) 

console.log(mergedObj)
// 9: {name: "樂購超市", storeToken: "xxx", storePosition: "Hangzhou"}

Read

判斷對象中是否有某個屬性

_.has(object, path)

let obj = {a: [{b: {c: 3}}]}
let hasC = _.has(obj, 'a[0].b.c')

console.log(hasC) // true

獲取對象中的某個屬性的值

_.get(object, path, [defaultValue])

let obj = {a: [{b: {c: 3}}]}
let c = _.get(obj, 'a[0].b.c')

console.log(c) // 3

Update

設置對象中的某個屬性的值

_.set(object, path, value)

let obj = {a: [{b: {c: 3}}]}
let newObj = _.set(obj, 'a[0].b.c', 4);

console.log(obj.a[0].b.c); // 4

對多個對象相同屬性的屬性值求和。

let customers = {
  new_customer: {0: 33, 1: 5, ... , 23: 0},
  old_customer: {0: 22, 1: 7, ... , 24: 0}
}
let customer = {}
let keys = _.keys(customers.new_customer)
let values = _.values(customers)
_.map(keys, key => {
  customer[key] = _.sumBy(values, key)
})

customers.customer = customer

console.log(customers)
// console
{
  customer: {0: 55, 1: 12, ... , 23: 0}
  new_customer: {0: 33, 1: 5, ... , 23: 0}
  old_customer: {0: 22, 1: 7, ... , 23: 0}
}

Number

生成一個隨機數，範圍n~m

_.random([lower=0], [upper=1], [floating])

let random1 = _.random(2, 5)
let random2 = _.random(5)

console.log(random1) // 2, 3, 4, 5
console.log(random2) // 0, 1, 2, 3, 4, 5

Data Type

判斷數據類型

_.isNumber(value)
_.isInteger(value)

...

_.isPlainObject(value)

let variable = 'hello';
// Number
console.log(_.isNumber(variable));
// Integer
console.log(_.isInteger(variable));
// Boolean
console.log(_.isBoolean(variable));
// String
console.log(_.isString(variable));
// Null
console.log(_.isNull(variable));
// Undefined
console.log(_.isUndefined(variable));
// Array
console.log(_.isArray(variable));
// Function
console.log(_.isFunction(variable));
// Object
console.log(_.isPlainObject(variable));
// Date
console.log(_.isDate(variable));

// DOM element
console.log(_.isElement(variable));

數據類型轉換

_.toArray
```
_.toArray('abc') // ["a", "b", "c"]
```

_.toInteger

_.toInteger(3.2); // 3
_.toInteger('3.2'); // 3

_.toNumber
```
_.toNumber('3.2') // 3.2
```

_.toString

_.toString(1); // "1"
_.toString([1, 2, 3]); // "1,2,3"

Util

重複屢次某個元素

_.times(n, [iteratee=_.identity])
```
const dateParams = _.times(2, () => '2018-08-27');
console.log(dateParams) // ["2018-08-27", "2018-08-27"]
```
p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; line-height: 19.0px; font: 13.0px 'Helvetica Neue'; color: #000000}

順便給媳婦打個廣告