Further Reading

Note that some of these resources are not specific to JavaScript. So you'll have to adapt them to JavaScript's syntax.

• MDN: Regular Expressions — documentation and examples
• stackoverflow: JavaScript regexp
• XRegExp — utility with features like metacharacter escaping, recursive matching, etc
• JSVerbalExpressions — construct regexp with natural language terms
• CommonRegexJS — collection of common regular expressions
• Awesome Regex — curated collection of libraries, tools, frameworks and software
• randexp.js — Generate strings that match a given regular expression
• stackoverflow: regex FAQ
  • stackoverflow: regex tag is a good source of exercise questions
• rexegg — tutorials, tricks and more
• regular-expressions — tutorials and tools
• regex101 and regexr — visual aid and online testing tool for regular expressions, select flavor as JavaScript before use
• regulex and debuggex — visualization of regexp as railroad diagrams
• regexcrossword — tutorials and puzzles
• swtch — stuff about regular expression implementation engines
• news.ycombinator: collection of regexp related resources

Here are some links for specific topics:

• rexegg: best regex trick
• regular-expressions: matching numeric ranges
• regular-expressions: Zero-Length Matches
• stackoverflow: Greedy vs Reluctant vs Possessive Quantifiers
• cloudflare: Details of the Cloudflare outage on July 2, 2019 — see appendix for details about CPU exhaustion caused due to regular expression backtracking