var arr = [1,2,3,4,5,6,7,8,9];
arr.splice(0,0,"test");

"test",1,2,3,4,5,6,7,8,9

"test",1,2,3,4,5,6,7,8

arr.splice(0,0,"test");
arr.pop();
arr.splice(1,0,"test2");
arr.pop();