The Gospel According to John is written to prove the deity of Jesus.
John 20:30-31 And many other signs truly did Jesus in the presence of his disciples, which are not written in this book: But these are written, that ye might believe that Jesus is the Christ, the Son of God; and that believing ye might have life through his name.
John only records seven of the miracles Jesus did, but they proved that He is who He claims to be….”God the Son”.