数据类型

Set - 作用和数组类似，和数组不同的是：不能存放重复元素

应用场景 - 数组去重

测试代码

//eg01:基本使用 //let set1 = new Set([10,10,3,0,39,0,99]); //console.log(set1) //eg02:数组去重 //let arr = [10,20,30,40,10,40,20]; //let set = new Set(arr); //console.log(set) //let arrNew = [...set]; //console.log(arrNew) //eg03：数组去重，把上面的操作变成一句话 let arr = [10,20,30,20,40,20,30]; let set = [...new Set(arr)] console.log(set)

数组解构赋值

就是把数组中每一个元素的值依次赋给变量 测试代码 //声明一个数组 let arr = [10,20,30,40]; //es5 /* let num1 = arr[0]; let num2 = arr[1]; let num3 = arr[2]; let num4 = arr[3]; console.log(num1,num2,num3,num4) */ //es6 //a //let [num1,num2,num3,num4] = arr; //console.log(num1,num2,num3,num4) //b. //let [num1,num2,num3,num4,num5] = arr; //console.log(num1,num2,num3,num4,num5) //c //let [num1,num2,num3,num4,num5=20] = arr //console.log(num1,num2,num3,num4,num5) //d //let [num1=100,num2,num3,num4,num5=20] = arr //console.log(num1,num2,num3,num4,num5)

展开运算符 - 数组展开

使用场景 * 数组拼接 * 利用Math.max()/Math.min() 测试代码

//eg01 /* let arr1 = [10,20,30]; let arr2 = [...arr,40,50]; console.log(arr1); console.log(arr2); */ //eg02 /* let arr1 = [10,20,30]; let arr2 = [40,50,60]; let arrNew = [...arr1,...arr2]; console.log(arrNew) */ //eg03 //求数组中的最大值 let arr1 = [3,9,5,7,4,6] //数据展开语法 let max2 = Math.max(...arr1); console.log(max2)