js数组扁平化、闭包、数组去重、判断一个对象是否是数组

//数组合并
let arr1 =[1,2,3,4,56]
let arr2 =[9,8,7,5,23]
arr1.push(arr2)
console.log(arr1.flat(1))
let arr3=[...arr1,...arr2]

//写一个闭包，每次调用+1
    function Fn(){
    var num=1;
    return function(){
    num++
    console.log(num)
    }
    }
    var Fn1=Fn()
    Fn1()
//数组去重
    let arr =[1,1,1,2,3,5,6,9,8,7,5,6,8,7,1,6,2,3,5]
    let array=[]
    for(var i =0;i<arr.length;i++){
        if(array.indexOf(arr[i])==-1){
            array.push(i)
        }
    }
    console.log(array)
    for(var i=0;i<arr.length;i++){
        if(!array.includes(arr[i])){
            array.push(arr[i])
        }
    }
    console.log(array)
//数组扁平化
    var arr =[1,1,2,3,[5,2,36,5,[2,0,20,20,5,51,54,,48],[,6262,0,0,]],[5,2,3,51,0,,22,0,0,215,],[6,020,3,01,]]
    console.log(arr.flat(5))
//判断一个对象是否是数组 是的话返回true  否则返回false
    var arr ={name:"1",age:2}
    var arr2 =[1,2,3]
    // console.log(Array.isArray(arr))
    console.log(Object.prototype.toString.call(arr)==='[object Array]')
    
    .....。