js中如何将多层嵌套的数组转换为一层数组

var newArr = []; // 用于存放转换后的数组
function arrOfOneDimension(arr) {
  for (let key of arr) {
    if (Array.isArray(key)) {
      arrOfOneDimension(key);//如果还是数组继续递归调用
    } else {
      newArr.push(key);
    }
  }
  return newArr;
}

let arr = [1,2,[3,4,[5,6],'7'],'a,b]cd']
console.log(arrOfOneDimension(arr)); //[1,2,3,4,5,6,'7','a,b]cd']

function parseArr(arr,res){
    var i=0;
    for(i=0;i<arr.length;i++){
        if(arr[i] instanceof Array){ // 是数组就递归调用上面的扁平化一层的代码
            parseArr(arr[i],res);
        }else{ // 不是数组，直接通过push添加到返回值数组
            res.push(arr[i]);
        }
    }
}
var a=[1,[2,[3,4]],5,6];
var res=[];
parseArr(a,res);

    var arr = ['mu','zi',['dig',['big','love']]]
    function flatten(arr){ 
        var res = []; 
        for(var i=0;i<arr.length;i++){
            if(Array.isArray(arr[i])){ // 是数组就递归调用上面的扁平化一层的代码
                res = res.concat(flatten(arr[i]));
            }else{ // 不是数组，直接通过push添加到返回值数组
                res.push(arr[i]);
            } 
        } 
        return res; 
    }
    console.log(flatten(arr))//["mu", "zi", "dig", "big", "love"]

// var arr1 = [1,[2,[5]],3,4] ==> arr1.toString(); '1,2,5,3,4'
//arr数组中的元素不能为字符串只能为数组
var newArr=arr.toString().split(',').map(function(ele){
    return +ele;
});
console.log(newArr)
alert(typeof arr[0]);  //number

    var arr = [1, [2, [3, 4],[5,[6],[7,8]]]];
    var arrStr = arr.toString();
    console.log(arrStr);// '1,2,3,4,5,6,7,8'
    var strArr = arrStr.split(',');
    console.log(strArr)// ["1", "2", "3", "4", "5", "6", "7", "8"]

Array.prototype.flatten=function(){
    return this.reduce(function(prev, cur) {
        var moreArr = [].concat(cur).some(Array.isArray(cur));  //判断cur是不是一个数组
        return prev.concat(moreArr ? cur.flatten() : cur);
    },[]);
};
var arr=a.flatten();

    //合并二维数组
    var twoArr = [['mu','zi'],['dig','big'],['lucky','jiji']];
    var oneArr = twoArr.reduce(function(total,currentValue){
        // console.log(total)
        return total.concat(currentValue);
    })
    console.log(oneArr);//["mu", "zi", "dig", "big", "lucky", "jiji"]

    var arr = [1,2,3,4,5,6,7,8,9,10]
    var str = arr.reduce(function(prev,cur,index,arr){
        return prev + cur ;
    })
    console.log(str)//55

function flatten(arr){
    let str = JSON.stringify(arr).replace(/(\[|\})/g, '');
    str = '[' + str + ']';
    arr = JSON.parse(str);
    return arr;
}

function flatten(arr){
    while(arr.some(item=>Array.isArray(item)){
        arr = [].concat(...arr);
    }
    return arr;
}

var arr = [1, [2, [3, 4]]];
console.log([].concat(...arr)); // [1, 2, [3, 4]]

[1, 2, [3, 4]].flat()
// [1, 2, 3, 4]

[1, 2, [3, [4, 5]]].flat()
// [1, 2, 3, [4, 5]]
[1, 2, [3, [4, 5]]].flat(2)
// [1, 2, 3, 4, 5]

[1, [2, [3]]].flat(Infinity)
// [1, 2, 3]

[1, 2, , 4, 5].flat()
// [1, 2, 4, 5]

// 相当于 [[2, 4], [3, 6], [4, 8]].flat()
[2, 3, 4].flatMap((x) => [x, x * 2])
// [2, 4, 3, 6, 4, 8]

        var arr = [1,6,7,8,9,10];
        function findFirstLargeNumber(item) {
            return item > 7;
        }
        console.log(arr.findIndex(findFirstLargeNumber)); // 3

        var arr = [1,6,7,8,9,10];
        console.log(arr.indexOf(8)); // 3