es6之复制数组

es5数组复制

      var arr=[1,2,3];
        var arr2=[];

        for(var i=0; i<arr.length; i++){
            arr2[i]=arr[i];
        }

        arr2.pop();

        console.log(arr, arr2);

es6数组复制

      var arr=[1,2,3];
        var arr2=Array.from(arr);
        arr2.pop();
        console.log(arr, arr2);
        //简写
        var arr=[1,2,3];
        var arr2=[...arr];
        arr2.pop();
        console.log(arr, arr2);