php loash,Lodash常用API笔记

lodash中文文档目前我只找到了3.10.x版本，现在lodash已经更新到4.17.x了，好多文档已经过期。而且lodash中api太多，有时候常用的几个我总是记不住名字，在这里贴出来，方便自己和大家。

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中的所有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中基础类型以外的类型，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}

注意一下如果没找到的话，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 = [{id: 0, name: "aaa", age: 33}]

_.map

从集合中挑出一个key，将其值作为数组返回

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

如果说上面是基础技能，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:也可以用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}

//]