Code Complexity Calculator

Cyclomatic complexity (CC) is a metric introduced by Thomas McCabe in 1976 that measures the number of linearly independent paths through a program. It equals 1 plus the number of decision points (if, else if, for, while, catch, &&, ||). A CC of 1–5 is simple and easy to test; 6–10 is moderate; 11–20 is high and should be refactored; 21+ is very high and difficult to maintain.

Higher cyclomatic complexity means more branches to test and more ways the code can fail. Research shows that code with CC above 10 has significantly higher defect rates. It's also harder to understand, maintain, and refactor. Keeping CC low makes unit testing easier, since each independent path ideally needs its own test case.

Industry guidelines from McCabe suggest keeping cyclomatic complexity at 10 or below per function. Google's style guides recommend keeping functions under 20. Code with CC above 20 is generally considered too complex for safe modification and should be broken into smaller functions.

Nesting depth counts how many levels deep your code goes with conditionals and loops — for example, an if inside a for loop inside another if is depth 3. Deep nesting (4+ levels) is a code smell that makes logic harder to follow. Use early returns, guard clauses, or extract inner blocks into helper functions to reduce nesting.

The tool auto-detects JavaScript, TypeScript, and Python based on syntax patterns. Cyclomatic complexity is calculated from decision keywords (if, for, while, catch, &&, ||, ? etc.) which are similar across these languages. The nesting depth calculation uses curly braces for JS/TS and indentation for Python.

Extract complex conditions into named boolean variables. Use early returns (guard clauses) instead of deeply nested if/else. Split long functions into smaller single-responsibility functions. Replace switch/if chains with lookup maps or polymorphism. Use libraries for common patterns (e.g., Array.filter/map instead of manual loops).