//                                    +---- From 0 to the index = (length - 1) - 4,
//                                    |     in this case index 3.
//                                  vvvvv
var array = [1,2,3,4,5,6,7,8].slice(0, -4);
console.log(array);

.as-console-wrapper { max-height: 100% !important; top: 0; }

var originalArr = [1, 2, 3, 4, 5, 6, 7, 8];

//                     +---- Is optional, for your case will remove 
//                     |     the elements ahead from index 4.
//                     v
originalArr.splice(-4, 4);
console.log(originalArr);

//----------------------------------------------------------------------

originalArr = [1, 2, 3, 4, 5, 6, 7, 8];
//                  +---- Omitting the second param.
//                  |     
//                  v
originalArr.splice(-4);
console.log(originalArr);

。作为控制台包装{最大高度:100%!重要;顶部:0;}

array = [1,2,3,4,5,6,7,8];
array1=array.filter((x,i)=>i<array.length-4);
console.log(array1);

array = [1,2,3,4,5,6,7,8];
array.splice(-4);
console.log(array);