ES6: Is it dangerous to delete elements from Set/Map during Set/Map iteration?

Safe code for new Set() may look like:

let items = [];
for (let item of set)
  if (isBad(item))
    items.push(item);
for (let item of items)
  set.delete(item)

Can I simplify code to:

for (let item of set)
  if (isBad(item))
    set.delete(item);

Safe code for new Map() may look like:

let keys = [];
for (let [key, val] of map)
  if (isBadKey(key) || isBadValue(val))
    keys.push(key);
for (let key of keys)
  map.delete(key)

Can I simplify code to:

for (let [key, val] of map)
  if (isBadKey(key) || isBadValue(val))
    map.delete(key)