根据属性值用 lodash 过滤对象数组

Question

我们有一个这样的对象数组

var myArr = [ {name: "john", age: 23},
              {name: "john", age: 43},
              {name: "jim", age: 101},
              {name: "bob", age: 67} ];

如何从 myArr 中获取名称为 john 和 lodash 的对象列表？

Answer 1

Lodash 有一个类似于 jQuerys 的“地图”功能：

var myArr =  [{ name: "john", age:23 },
              { name: "john", age:43 },
              { name: "jimi", age:10 },
              { name: "bobi", age:67 }];

var johns = _.map(myArr, function(o) {
    if (o.name == "john") return o;
});

// Remove undefines from the array
johns = _.without(johns, undefined)

Answer 2

使用lodash_.filter方法：

_.filter(collection, [predicate=_.identity])

遍历集合的元素，返回一个包含所有元素的数组，谓词返回真值。使用三个参数调用谓词： （值、索引|键、集合）。

将谓词作为自定义函数

 _.filter(myArr, function(o) { 
    return o.name == 'john'; 
 });

将谓词作为过滤对象的一部分（_.matches iteratee 简写）

_.filter(myArr, {name: 'john'});

将谓词作为 [key, value] 数组（_.matchesProperty iteratee 的简写。）

_.filter(myArr, ['name', 'John']);

文档参考：https://lodash.com/docs/4.17.4#filter

Answer 3

let myArr = [
    { name: "john", age: 23 },
    { name: "john", age: 43 },
    { name: "jim", age: 101 },
    { name: "bob", age: 67 },
];

let list = _.filter(myArr, item => item.name === "john");

Answer 4

与lodash:

const myArr = [ {name: "john", age: 23},
                {name: "john", age: 43},
                {name: "jim", age: 101},
                {name: "bob", age: 67} ];

const johnArr = _.filter(myArr, person => person.name === 'john');
console.log(johnArr)

原版 JavaScript：

const myArr = [ {name: "john", age: 23},
                {name: "john", age: 43},
                {name: "jim", age: 101},
                {name: "bob", age: 67} ];

const johnArr = myArr.filter(person => person.name === 'john');
console.log(johnArr);

Answer 5

lodash 还有一个 remove 方法

var myArr = [
    { name: "john", age: 23 },
    { name: "john", age: 43 },
    { name: "jim", age: 101 },
    { name: "bob", age: 67 }
];

var onlyJohn = myArr.remove( person => { return person.name == "john" })

Answer 6

let myArr = [
    { name: "john", age: 23 },
    { name: "john", age: 43 },
    { name: "jim", age: 101 },
    { name: "bob", age: 67 },
];

// this will return old object (myArr) with items named 'john'
let list = _.filter(myArr, item => item.name === 'jhon');

//  this will return new object referenc (new Object) with items named 'john' 
let list = _.map(myArr, item => item.name === 'jhon').filter(item => item.name);

Answer 7

**按姓名、年龄过滤** 也可以使用地图功能

地图和过滤器的区别

1. map - map() 方法使用为每个数组元素调用函数的结果创建一个新数组。 map 方法允许根据用户的喜好操作数组中的项目，在一个全新的数组中返回所选操作的结论。例如，考虑以下数组：

2。 filter - filter() 方法创建一个数组，其中填充了所有通过所提供函数实现的测试的数组元素。过滤器方法非常适合用户必须识别数组中具有共同特征的某些项目的特定情况。例如，考虑以下数组：

const users = [
    { name: "john", age: 23 },
    { name: "john", age:43 },
    { name: "jim", age: 101 },
    { name: "bob", age: 67 }
];

const user = _.filter(users, {name: 'jim', age: 101});
console.log(user);