var arr = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"];var sarr = [4,10,18];想得到5-9  11-17  19-最后想得到result 數(shù)組 var result = ["fghij","lmnopqr","tuvwxyz"];sarr可能的值sarr = [20] 得到21-最后 var result = ["vwxyz"];sarr = [20,24] 得到21-23 25-最后 var result = ["vwx","z"];求助js該怎么寫(xiě)