It looks like there's a small error in the sentence you've provided. The corrected version of the sentence would be:
"Would you mind if I didn't come to your party?"
This is indeed an expression asking for permission or, more specifically, it’s a polite way of asking if something would be acceptable or cause any inconvenience.
When you ask, “Would you mind...?” you're seeking permission or checking if the action you're considering would be bothersome to the other person. It’s a very polite, indirect way of asking about their feelings or getting consent.
For example:
- "Would you mind if I borrowed your book?"
- "Would you mind if I left early today?"