Vocal Type:Mezzo-Soprano 
Vocal Range: 3 octaves and 2 notes and a semi tone C#3- F6
Whistle Register: Yes 
Vocal Pluses: Jessie J has the ability to sing
 complex melisma without issue, and this is often noted as being a 
signature of her style. Along with this ability, she has the control to 
be able to sing trills, staccato notes and staccatissimo through complex
 melodies with pinpoint accuracy and uncanny pitch.
Jessie J's control, in regards to her vocal dexterity, is mirrored in 
her breath control.As a result she can hold notes for lengths of time 
without loss of quality to the sound , and sing complex and lengthy 
vocal lines in a single breath.
Strong mid-range that is solid, rounded, has a good dynamic to it and 
leads into the belting range effortlessly. The belting range  is elastic
 and energetic, being able to reach high into the fifth octave, with the
 aid of mixing. The head voice alone is spritely, of medium weight and 
is bright and easily accessible.
Vocal Negatives: Her technique sounds improper when reaching above an E5 and as a result her voice becomes shrill and unstable.

she has shown more higher notes and bigger range!!
RispondiEliminaand I hope you can update it and too add the longest note because she can really do long ones