版权声明：本文为个人知识整理，欢迎指正、交流、转载。 https://blog.csdn.net/u014711094/article/details/83151048
1 Util
- property propertyOf
let o = {a: {b: {c: 3}}}
// string形式较为明确、灵活
_.property('a.b.c')(o) // 3, recommendation
_.property(['a', 'b', 'c'])(o) // 3
// the opposite of property
_.propertyOf(o)('a.b.c') // 3
_.propertyOf(o)(['a', 'b', 'c']) // 3
// 注意下面的写法
_.property('a[b].c')(o) // 3
_.property(['a', 'b.c'])(o) // undefined
let o = {a: [1, {b: 2}]}
_.property('a[1].b')(o) // 2, recommendation
_.property('a.1.b')(o) // 2
_.property(['a', '1', 'b'])(o) // 2
- matchesProperty matches
let objs = {a: {b: 2, c: 3}}
// 深度比较(deep comparation)
_.matchesProperty('a', {b: 2})(o) // true
_.matches({b: 2})(o.a) // true
- property propertyOf matchesProperty matches用法示例
let objs = [{a: 1}, {a: 2, b: 2}, {a: 3}]
_.map(objs, _.property('a')) // [1, 2, 3]
_.map(objs, 'a') // 简写
_.reject(objs, _.matchesProperty('a', {b: 2})) // [{a: 1}, {a: 3}]
_.reject(objs, ['a', {b: 2}]) // 简写
_.reject(objs, ['a.b', 2]) // 简写
_.reject(objs, _.matches({b: 2})) // [{a: 1}, {a: 3}]
_.reject(objs, {b: 2}) // 简写
2 Collection
- map forEach forEachRight
let o = {a: 1, b: 2, c: 3}
// lodash将Arrry的部分方法extend到Object, 返回包含val的Array
// Object: (val, key, obj)相当于Array: (val, idx, arr)
_.map(o, (v, k, o) => k + v) // ['a1', 'b2', 'c3']
// each eachRight分别是forEach forEachRight的别名
// 输出: a1 b2
_.forEach(o, (v, k, o) => {
console.log(k + v)
return v < 2 // 停止遍历, 和Array.prototype.forEach不同
})
- some every filter reject find findLast
let o = {a: 1, b: 2, c: 3}
_.every(o, v => v > 2) // false
_.some(o, v => v > 2) // true
_.filter(o, v => v > 2) // [3]
_.reject(o, v => v > 2) // [1, 2]
_.find(o, v => v > 1) // 2
_.findLast(o, v => v > 1) // 3
let users = {
'barney': { 'age': 36, 'active': true },
'fred': { 'age': 40, 'active': false },
'pebbles': { 'age': 32, 'active': true }
}
// 原Arrry.prototype上的方法, 返回Array
// 回调的arguments是(val, key, obj)
_.every(users, 'active') // false
_.some(users, 'active') // true
_.filter(users, ['age', 40]) // [{'age': 40, 'active': false}]
_.filter(users, {'age': 40}) // [{'age': 40, 'active': false}]
_.reject(users, 'active') // [{'age': 40, 'active': false}]
_.find(users, 'active') // {'age': 36, 'active': true}
_.findLast(users, 'active') // {'age': 32, 'active': true}
3 Object
- findKey findLastKey mapKeys mapValues
let o = {a: 1, b: 2, c: 3}
// lodash为Object提供类似于Array的方法, 回调的参数是(val, key, obj)
// Object: (val, key, obj)相当于Array: (val, idx, arr)
_.findKey(o, v => v > 1) // 'b'
_.findLastKey(o, v => v > 1) // 'c'
_.mapKeys(o, (v, k) => k + v) // {a1: 1, b2: 2, c3: 3}
_.mapValues(o, v => v + 1) // {a: 2, b: 3, c: 4}