Lodash常用API筆記

Yujiaao 發(fā)布于2019-08-20 15:12 / 3409人閱讀

摘要：中文文檔目前我只找到了版本，現(xiàn)在已經(jīng)更新到了，好多文檔已經(jīng)過期。而且中太多，有時(shí)候常用的幾個(gè)我總是記不住名字，在這里貼出來，方便自己和大家。原生用法直接使用的根據(jù)條件去除某個(gè)元素。

lodash中文文檔目前我只找到了3.10.x版本，現(xiàn)在lodash已經(jīng)更新到4.17.x了，好多文檔已經(jīng)過期。而且lodash中api太多，有時(shí)候常用的幾個(gè)我總是記不住名字，在這里貼出來，方便自己和大家。

原生用法

直接使用的API

_.reject

根據(jù)條件去除某個(gè)元素。

var foo = [
    {id: 0, name: "aaa", age: 33},
    {id: 1, name: "bbb", age: 25}
]
var bar = _.reject(foo, ["id", 0])

//bar = [{id: 1, name: "bbb", age: 25}]

_.pick

根據(jù)第二個(gè)參數(shù)的key的數(shù)組，篩選第一個(gè)參數(shù)中的值并返回

var foo = {id: 0, name: "aaa", age: 33}
var bar = _.pick(foo, ["name", "age"])
//bar = {name: "aaa", age: 33}

_.keys

返回object中的所有key

var foo = {id: 0, name: "aaa", age: 33}
var bar = _.keys(foo)
//bar = ["id", "name", "age"]

_.cloneDeep

深度拷貝，這個(gè)不用多說了吧，js中基礎(chǔ)類型以外的類型，都會(huì)默認(rèn)拷貝備份
var bar = _.cloneDeep(foo)

_.find

查找數(shù)組

var foo = [
    {id: 0, name: "aaa", age: 33},
    {id: 1, name: "bbb", age: 25}
]
var bar = _.find(foo, ["id", 0])
//bar = {id: 0, name: "aaa", age: 33}

注意一下如果沒找到的話，會(huì)返回undefined，要處理一下

_.keyBy

以某個(gè)屬性為鍵，將數(shù)組轉(zhuǎn)為對(duì)象

var foo = var foo = [
    {id: 0, name: "aaa", age: 33},
    {id: 1, name: "bbb", age: 25}
]
var bar = _.keyBy(foo, "name")
//bar = {
//    aaa: {id: 0, name: "aaa", age: 33},
//    bbb: {id: 1, name: "bbb", age: 25}
//}

_.filter

根據(jù)條件過濾出符合條件的元素，返回新數(shù)組

var foo = var foo = [
    {id: 0, name: "aaa", age: 33},
    {id: 1, name: "bbb", age: 25}
]
var bar = _.filter(foo, ["name", "aaa"])
//bar = [{id: 0, name: "aaa", age: 33}]

_.map

從集合中挑出一個(gè)key，將其值作為數(shù)組返回

var foo = var foo = [
    {id: 0, name: "aaa", age: 33},
    {id: 1, name: "bbb", age: 25}
]
var bar = _.map(foo, "name")
//bar = ["aaa", "bbb"]

_.max/_.min/_.sum

數(shù)組中最大值、最小值、數(shù)組求和

var foo = [1, 2, 3, 4]
var bar = _.max(foo)
//bar = 4
bar = _.min(foo)
//bar = 1
bar = _.sum(foo)
//bar = 10

_.pad/_.padStart/_.padEnd

在兩端、開頭、末尾補(bǔ)齊字符

var foo = "helloworld"
var bar = _.pad(foo, 14, "-")
//bar = --helloworld--
bar = _.padStart(foo, 14, "-")
//bar = ----helloworld
bar = _.padEnd(foo, 14, "-")
//bar = helloworld----

組合用法

如果說上面是基礎(chǔ)技能，那么下面奉上幾個(gè)炫酷的組合技：

選出json數(shù)組中id最大的一項(xiàng)

var foo = [
    {id: 0, name: "aaa", age: 33},
    {id: 1, name: "bbb", age: 25}
]
var bar = _.find(foo, ["id", _.max(_.map(foo, "id"))])
// bar = {id: 1, name: "bbb", age: 25}

ps:也可以用maxBy某個(gè)key來代替

更新json數(shù)組中某一項(xiàng)的值

var foo = [
    {id: 0, name: "aaa", age: 33},
    {id: 1, name: "bbb", age: 25}
]
let list = _.keyBy(foo, "id")
list[0].name = "ccc"
var bar = _.map(list)
// bar = [
//    {id: 0, name: "ccc", age: 33},
//    {id: 1, name: "bbb", age: 25}
//]