Complexity Analyzer
Quick Start
Analyze complexity with tools:
# JavaScript
npx eslint --plugin complexity --rule 'complexity: [error, 10]' src/
# Python
pip install radon
radon cc src/ -a -nb
# General
npx complexity-report src/Instructions
Step 1: Calculate Cyclomatic Complexity
Count decision points + 1:
- if, else, elif
- for, while loops
- case statements
- && and || operators
- ternary operators
- catch blocks
Example:
function example(x) { // +1 (base)
if (x > 0) { // +1
return x;
} else if (x < 0) { // +1
return -x;
}
return 0;
}
// Complexity: 3Step 2: Identify Complex Functions
| Complexity | Rating | Action |
|---|---|---|
| 1-10 | Simple | No action needed |
| 11-20 | Moderate | Consider refactoring |
| 21-50 | Complex | Should refactor |
| 50+ | Very Complex | Must refactor |
Step 3: Analyze Cognitive Complexity
Cognitive complexity considers:
- Nesting depth (each level adds to complexity)
- Breaks in linear flow (if, loops, catch)
- Recursion
// Cyclomatic: 4, Cognitive: 7
function sumOfPrimes(max) { // +0
let total = 0;
for (let i = 2; i <= max; i++) { // +1 (loop)
let isPrime = true;
for (let j = 2; j < i; j++) { // +2 (nested loop)
if (i % j === 0) { // +3 (nested if)
isPrime = false;
break; // +1 (break)
}
}
if (isPrime) { // +1 (if)
total += i;
}
}
return total;
}Step 4: Generate Report
## Complexity Report
### High Complexity (>20)
**processOrder()** - src/orders.js:45
- Cyclomatic: 28
- Cognitive: 35
- Lines: 127
- Recommendation: Extract validation, calculation, and persistence logic
**validateUser()** - src/auth.js:12
- Cyclomatic: 22
- Cognitive: 28
- Lines: 89
- Recommendation: Extract individual validation rules
### Moderate Complexity (11-20)
[List functions with complexity 11-20]Simplification Strategies
Extract Method
// Before: Complexity 15
function processData(data) {
if (data.type === 'A') {
// 20 lines of processing
} else if (data.type === 'B') {
// 20 lines of processing
}
}
// After: Complexity 3
function processData(data) {
if (data.type === 'A') return processTypeA(data);
if (data.type === 'B') return processTypeB(data);
}Replace Nested Conditionals
// Before: Cognitive 12
function getPrice(user, product) {
if (user) {
if (user.isPremium) {
if (product.onSale) {
return product.price * 0.7;
} else {
return product.price * 0.9;
}
}
}
return product.price;
}
// After: Cognitive 4
function getPrice(user, product) {
if (!user || !user.isPremium) return product.price;
if (product.onSale) return product.price * 0.7;
return product.price * 0.9;
}Use Polymorphism
// Before: Complexity 8
function getArea(shape) {
if (shape.type === 'circle') {
return Math.PI * shape.radius ** 2;
} else if (shape.type === 'square') {
return shape.side ** 2;
}
// ... more types
}
// After: Complexity 1 per class
class Circle {
getArea() { return Math.PI * this.radius ** 2; }
}
class Square {
getArea() { return this.side ** 2; }
}