Regex Test Case Runner

Build a small repeatable regex test set in the browser and keep flavor differences explicit before porting the pattern to another language.

Pattern

Flags

Cases: + should match, - should not match

ReadyEach case is tested independently with RegExp.lastIndex reset before the next case.

Before reusing a regular expression

keeps the established regex widgets and worker-guarded execution paths intact while connecting testing, explanation, extraction, replacement, test cases, static risk review, and code generation. Pattern data stays in the browser, and the shared inspector can save an explicit pattern locally.

Regex flavor and performance boundaries

Interactive checks follow the JavaScript RegExp implementation available in the current browser unless a tool explicitly says otherwise. Token explanations and backtracking warnings are bounded static guidance, not PCRE/Python/.NET compatibility, formal complexity analysis, or proof that a pattern is safe for every possible input.