push and pop are more efficient than shift and unshift@H_301_1@

since shift and unshift need to re-index@H_301_1@

push O(1)
pop O(1)
shift O(N)
unshift O(N)
concat O(N)
slice O(N)
splice O(N)
sort O(NlogN)
forEach/map/filter/reduce... O(N)@H_301_1@ 原文链接：https://www.f2er.com/note/411475.html