about v-chip-group's behavior

[iisyos]

I'm using v-chilip-group for chose some presets.
Catch the preset change by @change, and show [Yes or No dialog] by confirm ( javascript regular function. ) .
Then,I have a trouble.
Although I choose No in dialog,the preset is changed.
But previously preset is still active(chacked by console.log(activePreset))!!!!!!!!!

Why!?!?
I dont wanna change active preset if I choose No....
Could anyone please give me solution!

Sorry for Bad question...
Im vue biginnner...