[Refactor] Handle pathological strings better in 5/ToNumber #68
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Improve input string that are pathological by virtue of containing lots of whitespace but not at the end or start of the string. Such strings can lead to quadratic runtime of the regular expression present in the `ToNumber` implementation, unnecessarily consuming computational resources. This patches addresses the problem by ensuring that the string does end with a whitespace character before removing whitespace character from the end of the string. This ensures that pathological inputs cannot cause quadratic runtime because such inputs won't reach the regular expression. An alternative solution would be to have a negative lookbehind in the regular expression. But, following related patches in related projects I opted for the above solution.
Member
|
If there's no regression test I'm not sure it's worth fixing. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Improve input string that are pathological by virtue of containing lots of whitespace but not at the end or start of the string. Such strings can lead to quadratic runtime of the regular expression present in the
ToNumberimplementation, unnecessarily consuming computational resources.This patches addresses the problem by ensuring that the string does end with a whitespace character before removing whitespace character from the end of the string. This ensures that pathological inputs cannot cause quadratic runtime because such inputs won't reach the regular expression.
An alternative solution would be to have a negative lookbehind in the regular expression. But, following related patches in related projects (es-shims/String.prototype.trim#13 and es-shims/String.prototype.trimEnd#6) I opted for the above solution.