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  • [转] Lodash常用API笔记


    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 = {
    //    aaa: {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}
    //]
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  • 原文地址:https://www.cnblogs.com/chris-oil/p/8624466.html
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