regexp/no-super-linear-backtracking

Heuristically flags regex literals that may cause super-linear (catastrophic) backtracking.

• Category: Plugin (built-in)
• Default: off

Config (both forms accepted):

pluginRules: { 'no-super-linear-backtracking': 'error' }
// or
pluginRules: { 'regexp/no-super-linear-backtracking': 'error' }

Patterns flagged include:

• Adjacent unlimited quantifiers that can exchange characters (e.g., .*\s*, \s*.*, .+?\s*)
• Repeated unlimited wildcards (e.g., .*.*)
• Nested unlimited quantifiers (e.g., (.+)+)

Example:

const r = /(.*)(.*)/ // flagged

Safer alternatives

• Use specific character classes and limits: ([\w-]+)\s+([\w-]+)
• Avoid overlapping unlimited quantifiers. Where necessary, add anchors or make quantifiers reluctant with bounded context.

Best practices

• Keep this rule at error in performance-sensitive code (routers, parsers)
• Add tests for worst-case regex inputs to catch regressions
• Prefer explicit tokenization over complex single-shot regexes when performance is critical