快来看JS的的几个常用算法（持续更新中）

灰太狼 2021-09-29 05:36 188阅读 0赞

### 数组去重 ###

// 第一种方法
    	let arr = [1,1,2,3,4];
    	function fun(v) { 
    		return Array.from(new Set(v))
    	}
    	console.log(fun(arr)) //[1,2,3,4]
    	// 第二种方法
    	let qc= [...new Set(arr)]
      console.log(qc) //[1,2,3,4]

### 数组并集 ###

let arr0 = ['a','b','c'];
    	let arr2 = ['c','d'];
    	let a=new Set(arr0);
    	let b=new Set(arr2);
    	let bj = new Set([...a,...b]);
      console.log(bj);//{"a", "b", "c", "d"}

### 数组交集 ###

let jj = new Set([...a].filter(x=>b.includes(x)));
      console.log(jj);//{"c"}

### 数组差集 ###

let cj = new Set([...a].filter(x=>!b.includes(x)));
      console.log(cj);//{"a", "b"}

### 统计数组相同项的个数 ###

### 数组方法reduce()实现filter、map ###

let arr7=[2,3,10];
    	const arro=arr7.reduce(function(list,num){ 
    		num=num*2;
    		if(num>=20){ 
    			list.push(num)
    		}
    		return list;
    	},[])
      console.log(arro);//[20]

### 字符串转换为数字 ###

let num1='1' * 1;
      console.log(typeof num1) //number

### 使用Boolean过滤数组中的所有假值 ###

let jz=[0,null,false,NaN,1,2];
    	const filter1=arr1=>arr1.filter(Boolean);
      console.log(filter1(jz)) //[1,2]

### 取整 ###

let num2=1.223;
      console.log(num2|0);//1

### 判断奇偶 ###

let num3=3;
      console.log(!!(num3 & 1));//true

### 精确到指定位数(取小数第一位) ###

let num4=6.222;
      console.log(num4.toFixed(1));//6.2

### 解构 ###

let [rr,aa]=[1,2];
      console.log(rr);//1

### 使用解构交换数值 ###

[rr,aa]=[aa,rr];
      console.log(rr);//2

### 判断数据类型 ###

let ee=[1,12];
    	let ongjj={ 
    		name:'maomin'
    	}
    	function isType(arr) { 
        	return Object.prototype.toString.call(arr) 
    	}	
    	console.log(isType(ee));//[object Array]
      console.log(isType(ongjj));//[object Object]

### 字符串转化为对象 ###

let stringobj='{"id":0,"name":"张三","age":12}';
    	let d3=JSON.parse(stringobj);
      console.log(d3)//{id: 0, name: "张三", age: 12}

### 对象转化为字符串 ###

let objj={ 
    		id:0,
    		name:'maomin'
    	}
    	let d4=JSON.stringify(objj)
      console.log(d4);//{"id":0,"name":"maomin"}

### 字符串转化为数组 ###

let stringww="a,b,c,d,e,f";
      console.log(stringww.split(","))//["a", "b", "c", "d", "e", "f"]

### 数组转化为字符串 ###

let arr9=['l','o','v','e'];
      console.log(arr9.join('-'))

### 去除字符串指定符号 ###

var stre="a,b,c,d";
    	function clear(str) {  
    		str = str.replace(/,/g, "");//取消字符串中出现的所有逗号 
    		return str; 
    	}
    	console.log(clear(stre))//abcd