js数组倒序输出

1. var arr1 = [1,2,3,4];

    var arr2 = [];

    for(var i=0;i<=arr1.length;i++){

            arr2.push(arr1.pop())

    }

     arr2.push(arr1[0]);

     console.log(arr2);

2. var arr1 = [1,2,3,4];

    for(var i=arr1.length;i>=0;i--){   

      console.log(arr1[i]);

   }

3. var arr1 = [1,2,3,4];

    console.log(arr1.reverse());