Lets say I have an object
filter: { \"ID\": false, \"Name\": true, \"Role\": false, \"Sector\": true, \"Code\": false }
Well here's a one-liner with vanilla JS:
Object.keys(filter).forEach(v => filter[v] = false)
It does use an implicit loop with the .forEach() method, but you'd have to loop one way or another (unless you reset by replacing the whole object with a hardcoded default object literal).
.forEach()