let arr = [2,4,434,43];

let arr1= arr.slice();
//let arr1 = arr.slice(0);

arr[0] = 'a';

console.log(arr,arr1); // [a,4,434,43] [ 2, 4, 434, 43 ]

Array.prototype.clone = function(){

    let a=[];

    for(let i=0,l=this.length;i<l;i++) {

        a.push(this[i]);

    }

    return a;

}

let arr = ['aaa','bbb','ccc','wwwww','ddd'];
arr[0] = 'a';

let arr2 = arr.clone();

console.log(arr,arr2);//['a','bbb','ccc','wwwww','ddd']  ['aaa','bbb','ccc','wwwww','ddd']

Array.prototype.clone=function(){

    return [].concat(this);

    //或者 return this.concat();
　　 //或者 return this.concat([]);

}

let arr = ['aaa','asss']

let arr1 = arr.clone()

arr[0] = 123

console.log(arr,arr1)//[123,'asss']  ['aaa','asss']

let arr = ['sdsd',123,123,123]

let arr1 = []

Object.assign(arr1,arr)

arr[1] = 'aaaa'

console.log(arr,arr1) // [ 'sdsd', 'aaaa', 123, 123 ] [ 'sdsd', 123, 123, 123 ]

const a1 = [1, 2];

const a2 = [...a1];

a1[0] = 'aaa'

console.log(a1,a2)// ['aaa',2]　　[1,2]