[转] Lodash经常使用API笔记

 

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原生用法

直接使用的API

_.reject

根据条件去除某个元素。

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

根据第二个参数的key的数组，筛选第一个参数中的值并返回

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

_.keys

返回object中的全部key

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

_.cloneDeep

深度拷贝，这个不用多说了吧，js中基础类型之外的类型，都会默认拷贝备份
var bar = _.cloneDeep(foo)

_.find

查找数组

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}

注意一下若是没找到的话，会返回undefined，要处理一下

_.keyBy

以某个属性为键，将数组转为对象

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

根据条件过滤出符合条件的元素，返回新数组

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

_.map

从集合中挑出一个key，将其值做为数组返回

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

数组中最大值、最小值、数组求和

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

在两端、开头、末尾补齐字符

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

组合用法

若是说上面是基础技能，那么下面奉上几个炫酷的组合技：

选出json数组中id最大的一项

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:也能够用maxBy某个key来代替

更新json数组中某一项的值

 

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} //]