As you can see, Jessica has quite a Diamond Shaped Face, meaning that she has a narrow chin with narrow forehead. In that case, she tends to wear medium length hairstyles to long hairstyles. 
Notice that Jessica tends to wear pretty heavy volumed hairstyles, with long tight fringes, covering up her forehead. That technique softens up her narrow forehead. Hence, it makes it look like an oval shaped face.
Jessica loves to play around with different hair colours. Her dyed hairstyles in addition to her beautiful figure makes her extremely gorgeous. Her hairstyles that lack fringe gives her a wilder look. With fringes she looks even more cute than she is already.
As you can see again, Jessica frequently wears hairstyles that contain heavy fringes. One could say heavy fringes gives a girl the cuter charisma.