Requirements: Due to too much data passed in from the backend, the frontend needs to calculate the maximum and minimum values of a certain value in the array. Isn’t the most commonly used method is to compare after traversal, or use the sort method to achieve, A colleague gave me a trick. You can get the maximum and minimum values in the array object in one sentence . That is to use the linq plug-in . It is really easy to use and the usage is very simple, so I will share it with you~
1. Find the maximum and minimum values of a property of an array object
Method 1, use the linq plugin
1.1 Download first
npm install linq -S1.2 Import, can be local or global, according to your own needs
import Enumerable from 'linq';1.3 use
const items: [
{ id: 0, value: -5 },
{ id: 1, value: 10 },
{ id: 2, value: -15 },
{ id: 3, value: 44 },
{ id: 4, value: 44 },
{ id: 5, value: -5 }
],
// 筛选最大值和最小值
const min = Enumerable.from(this.items).min(item => item.value);
const max = Enumerable.from(this.items).max(item => item.value);
Method 2, use math to implement, this method is not good, and it needs to be screened
let arr=[2,4,56,5,7,33];
var obj=Math.max.apply(null,arr);
var min=Math.min.apply(null,arr);
console.log(obj,'最大值')
console.log(min,'最大值')2. Filter the required value according to the condition
// 条件筛选出偶数，得到的值一定是满足where中条件的
const arr = [1, 2, 3, 4, 5];
this.result = Enumerable.from(arr)
.where(x => x % 2 === 0)
.toArray();
console.log(this.result); // [2, 4]3. Deduplication of array objects
const items= [
{ id: 0, value: -5 },
{ id: 1, value: 10 },
{ id: 2, value: -15 },
{ id: 3, value: 44 },
{ id: 4, value: 44 },
{ id: 5, value: -5 }
// { id: 3, value: "-220" }
],
// linq的去重
this.quchong = Enumerable.from(this.items)
.distinct(item => item.value)
.toArray();
4. Filter and query specific values, which is the function of filter
// 筛选查询特定的值
this.select = Enumerable.from(this.items)
.select(item => item.value)
.toArray();
5. Ascending and descending function
var myList = [
{ Name: 'Jim', Age: 20 },
{ Name: 'Kate', Age: 21 },
{ Name: 'Lilei', Age: 18 },
{ Name: 'John', Age: 14 },
{ Name: 'LinTao', Age: 25 }
];
this.orderByup = Enumerable.from(this.items)
.orderBy(x => x.value)
.toArray(); //升序
this.orderBydown = Enumerable.from(myList)
.orderByDescending(x => x.Age)
.toArray(); //降序
6. Complete example code
<template>
<div class="content-box">
<div class="container">
<span>原数组{
{ items }}</span>
<br />
<span>最小值：{
{ min }}，最大值：{
{ max }}</span>
<br />
<span>筛选后的值{
{ result }}</span>
<br />
<span>去重后的数组{
{ quchong }}</span>
<br />
<span>只要value的值{
{ select }}</span>
<br />
<span>升序:{
{ orderByup }}</span>
<br />
降序：{
{ orderBydown }}
</div>
</div>
</template>
<script>
import Enumerable from 'linq';
export default {
data() {
return {
items: [
{ id: 0, value: -5 },
{ id: 1, value: 10 },
{ id: 2, value: -15 },
{ id: 3, value: 44 },
{ id: 4, value: 44 },
{ id: 5, value: -5 }
// { id: 3, value: "-220" }
],
min: 0,
max: 0,
result: [],
quchong: [],
select: [],
groupBy: [],
orderByup: [],
orderBydown: []
};
},
mounted() {
this.query();
},
methods: {
query() {
// 筛选最大值和最小值
this.min = Enumerable.from(this.items).min(item => item.value);
this.max = Enumerable.from(this.items).max(item => item.value);
// 条件筛选出偶数，得到的值一定是满足where中条件的
const arr = [1, 2, 3, 4, 5];
this.result = Enumerable.from(arr)
.where(x => x % 2 === 0)
.toArray();
console.log(this.result); // [2, 4]
// linq的去重
this.quchong = Enumerable.from(this.items)
.distinct(item => item.value)
.toArray();
// 筛选查询特定的值
this.select = Enumerable.from(this.items)
.select(item => item.value)
.toArray();
// 分组
var myList = [
{ Name: 'Jim', Age: 20 },
{ Name: 'Kate', Age: 21 },
{ Name: 'Lilei', Age: 18 },
{ Name: 'John', Age: 14 },
{ Name: 'LinTao', Age: 25 }
];
this.orderByup = Enumerable.from(this.items)
.orderBy(x => x.value)
.toArray(); //升序
this.orderBydown = Enumerable.from(myList)
.orderByDescending(x => x.Age)
.toArray(); //降序
var array1 = [1, 412, 5, 3, 5, 412, 7];
var array2 = [20, 12, 5, 5, 7, 310];
const except = Enumerable.from(array1).except(array2).toArray(); //结果3,412,1
console.log(except, '取差集，差集就是俩个数组中不相同的值');
var array1 = [1, 412, 5, 3, 5, 412, 7];
var array2 = [20, 12, 5, 5, 7, 310];
const intersect = Enumerable.from(array1).intersect(array2).toArray();
//结果5,7
console.log(intersect, '取交集，交集就是俩个数组相同的值');
}
}
};
</script>
<style lang="scss" scoped></style>
That’s about all the commonly used ones, and there are some other methods you can explore by yourself~ This is the end of the article, I hope it will be helpful to you~