MaximeKjaer/js-collections

State of JavaScript iterable collections

State of JavaScript iterable collections

The following document keeps track of the available methods on JavaScript collections. This is still very much an early draft, and may contain errors! Further work is needed to explain why some methods don't make sense, rule more methods out, and add links to relevant MDN documentation or TC39 proposals.

Legend:

• ✅ means that there is specification for this
• 🚀 means that there is a proposal for this
• ❓ means that the feature may make sense, but no proposal exists
• 🚧 means that the feature doesn't make sense
• 👴 means that the feature has been deprecated

Modification

	Array	Set	Map	IterableIterator
concat, union	✅	❓	❓	❓
dropWhile	❓	🚧	🚧	❓
filter	✅	❓	❓	❓
flatMap	🚀	❓	❓	❓
flatten	🚀	❓	❓	❓
intersection	❓	❓	❓	❓
map	✅	❓	❓	❓
takeWhile	❓	❓	❓	❓
unique	❓	🚧	❓	❓

Reduction

	Array	Set	Map	IterableIterator
every	✅	❓	❓	❓
find	✅	❓	❓	❓
findIndex	✅	❓	❓	❓
includes, has	✅	✅	✅	❓
join	✅	❓	❓	❓
max	❓	❓	❓	❓
min	❓	❓	❓	❓
reduce	✅	❓	❓	❓
reduceRight	✅	🚧	🚧	❓
some	✅	❓	❓	❓
sum	❓	❓	🚧	❓

Comparison

	Array	Set	Map	IterableIterator
disjoint	❓	❓	❓	❓
equals	❓	❓	❓	❓
intersects	❓	❓	❓	❓

Reorganization

	Array	Set	Map	IterableIterator
chunks	❓	❓	❓	❓
shuffle	❓	🚧	🚧	❓
slice	✅	🚧	🚧	❓
unzip	❓	❓	🚧	❓
zip	❓	❓	🚧	❓

Construction

	Array	Set	Map	IterableIterator
fill	✅	❓	❓	❓
from	✅	🚀	🚀	❓
of	✅	🚀	🚀	❓
range	❓	❓	🚧	❓

Iteration

	Array	Set	Map	IterableIterator
entries	✅	✅	✅	❓
for ... in	✅	🚧	❓	❓
for ... of	✅	✅	✅	❓
forEach	✅	✅	✅	❓
keys	✅	🚧	✅	❓
values	✅	✅	✅	❓

Notes

WeakSet and WeakMap

WeakSet and WeakMap are not iterable, and thus aren't included in this list. See #1 for more information.