String: var s = “1,2,3,4,5,”

Target: delete the last ”,”

**Methods: **S = s.s ubstring (0, s.L ength - 1);

Var s2 = “img/upload/123.jpg”

Target: get the file name (not including the suffix)

**Methods: **S2 = s2. The substring (s2) lastIndexOf (’/’) + 1, s2. The lastIndexOf (’. ’));