JavaScript Split String with regex – match (how to replace match regex into split function)

let s = "AbcDefGH"
s.match(/[A-Z]+[a-z]*/g)
["Abc", "Def", "GH"] // This is what expecting with split function

s.split(/(?=[A-Z]+[a-z]*)/g)
["Abc", "Def", "G", "H"] // "G" and "H" are separated.

My Question is how can I replace match regex into split function to get the same result of match.

Please explain what for ?= when match regex is translated to split function

Thanks