面试算数

多维数组变1维

const arr = [1, 2, [2, 3, [3, 5]]];
方法1：
function arrOne(arr) {
    return arr.reduce(function(total, currentVal) {
        return total.concat(Array.isArray(currentVal) ? arrOne(currentVal) : currentVal)
    }, [])
}
console.log(arrOne(arr))
方法2：
arr.flat(999)

获取DOM最大深度

function getDepth(dom){
   if(!dom.children||dom.children.length==0){
   		return 1
   }
   const nextDepths = [...dom.children].map(item=>{
   		return getDepth(item)
   })
   return 1 + Math.max(...nextDepths)
}

获取数组维度 [1, 2, 3, [4], [[6], [5]]].getLevel()

 Array.prototype.getLevel = function() {
   if(this.length==0){
   		return 1
   }
   let nextLevel = this.map(item=>{
   		return Array.isArray(item)?item.getLevel():0
   	})
   	return 1+Math.max(...nextLevel)
};
Array.prototype.getLevel = function() {
   let arr = this;
    let j = 1
    for (let item of arr) {
        if (Array.isArray(item)) {
            if (1 + item.getLevel() > j) {
                j = j + item.getLevel()
            }
        }
    }
    return j
};
Array.prototype.getLevel = function() {
    let arr = this
    let arrJson = JSON.stringify(arr)
    let nowArr = arrJson.replace(/[0-9]/g, "").replace(/,/g, "")
    let i = 0;
    return removeO(nowArr)

    function removeO(arr) {
        if (arr.indexOf('[]') != -1) {
            i++
            removeO(arr.replace(/\[\]/g, ""))
        }
        return i
    }

}

[1, 1, ‘1’, ‘1’, null, null, undefined, undefined, new String(‘1’), new String(‘1’), /a/, /a/, NaN, NaN]

返回：
[1, ‘1’, null, undefined, new String(‘1’), /a/, NaN]

let arr = [1, 1, '1', '1', null, null, undefined, undefined, new String('1'), new String('1'), /a/, /a/, NaN, NaN, ]

let map = new Map()
for (let i = 0; i < arr.length; i++) {

    if (typeof arr[i] == 'object') {
        if (arr[i] instanceof RegExp) {
            map.set(arr[i].toString(), arr[i])
        } else {
            map.set(JSON.stringify(arr[i]), arr[i])
        }
    } else {
        map.set(arr[i], arr[i])
    }
}
for (let [key, value] of map) {
    console.log(value)
}