Cody, 9, was diagnosed with Systemic Juvenile Idiopathic Arthritis (SJIA) when he was 2 and a half.
SJIA is an auto-inflammatory disease where the immune system attacks healthy tissues and cells. Cody is medicated constantly and receives a transfusion through his portacath every two to four weeks.
When he has flare-ups or his body starts attacking itself, he can go from fine to being in Starship Hospital within 24 hours. That means he misses a lot of school, attending on average just three days a week.
"There are many worthy charities out there but she [Jessica] was really touched by Cody's story," Mrs Back said. "It's a personal cause . . . we will see where the money is going, and the difference it's going to make."
This week at Salon St Bruno, the proud Back family along with Cody and his mum, Danielle Love, watched as the cape went on and the scissors came out.
Jessica's bubbly laughter was briefly replaced by a quivering lip as her long, brown pigtails were handed to her. But seconds later the smile returned and she gave a wee twirl to show off her new chin length bob.
Ms Love said when the Backs first told her what Jessica wanted to do she couldn't believe it.
"Honestly when they first said it I didn't know what to say. I actually said no, I was overwhelmed.
"I was blown away by Jess' generosity . . . just to even think that Cody's journey could touch other people."
Cody was "speechless", she said.
"For someone of a similar age to see his struggles and want to help. He welled up a little bit [when he heard]," Ms Love said.
So far the Givealittle page 'Jessica's haircut' has raised more than $2700 from 34 donors.
Ms Love said the money would be used to get Cody extra tutoring so he doesn't fall behind at school and help with the costs of the regular trips to Starship Hospital.
"I wanted Jess to see exactly what it's going to."
She said it had been a lonely journey at times for Cody's dad, Shane Love, and herself, although for their son "the struggle is normal".
"I just can't say thank you enough."
But was Cody pleased by the prospect of extra school lessons?
"Yeah but no," he shrugged.
To help Cody go to https://givealittle.co.nz/cause/cuts4cody.