splice

var a = ["1","2","3"]
undefined
a.splice
splice() { [native code] }
a.splice(2,1)
["3"]
a
["1", "2"]
a.splice(2,0,"44")
[]
a
["1", "2", "44"]
a.splice(12,0,"44")
[]
a
["1", "2", "44", "44"]