loadsh 常用方法解析

• _.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 object = { 'a': 1, 'b': '2', 'c': 3 };
 
_.pick(object, ['a', 'c']);  
// => { 'a': 1, 'c': 3 }

• _.pickBy
  根据第二个参数条件，筛选出符合条件的值

var object = { 'a': 1, 'b': '2', 'c': 3 };
 
_.pickBy(object, _.isNumber);
// => { 'a': 1, 'c': 3 }

• _.omit
  根据第二个参数，筛选第一个参数中独有的元素

var object = { 'a': 1, 'b': '2', 'c': 3 };

_.omit(object, ['a', 'c']);  // => { 'b': '2' }

• _.omitBy
  根据第二个参数条件，筛选出不符合第二个参数条件的元素

var object = { 'a': 1, 'b': '2', 'c': 3 };
 
_.omitBy(object, _.isNumber);
// => { 'b': '2' }

• _.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}]

• _.keys
  返回object中的所有key
  

  _.key()

• _.keyBy
  以某个属性为键，将数组转为对象

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}
//}

• _.cloneDeep
  深拷贝

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

• _.filter
  根据条件过滤出符合条件的元素，返回新数组

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 = [
    {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----

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}