A modern TypeScript/JavaScript compiler plugin for automatic tail call optimization
npm install js-tail-recursion-opt-plugin



A modern TypeScript/JavaScript compiler plugin that automatically optimizes tail-recursive functions into efficient loops at compile time.
> โก Production Ready โข ๐งช 100% Test Coverage โข ๐ Zero Runtime Overhead
- โ
Automatic Detection: Scans your code for tail-recursive patterns
- โ
Loop Transformation: Converts tail calls to while loops for better performance
- โ
Stack Overflow Prevention: Eliminates stack overflow issues with deep recursion
- โ
TypeScript Support: Full TypeScript compatibility
- โ
Zero Runtime Overhead: Optimization happens at compile time
- โ
Configurable: Control which functions to optimize with annotations
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Comprehensive Testing: Extensive test suite ensures correctness
``bash`
npm install --save-dev js-tail-recursion-opt-pluginor
yarn add -D js-tail-recursion-opt-plugin
Add the plugin to your Babel configuration:
.babelrc
`json`
{
"plugins": ["js-tail-recursion-opt-plugin"]
}
babel.config.js
`javascript`
module.exports = {
plugins: ['js-tail-recursion-opt-plugin']
};
`javascript`
{
"plugins": [
["js-tail-recursion-opt-plugin", {
"debug": false,
"onlyAnnotated": false,
"annotationTag": "@tail-recursion"
}]
]
}
Before:
`javascript
function factorial(n, acc = 1) {
if (n <= 1) return acc;
return factorial(n - 1, n * acc);
}
factorial(10000); // โ RangeError: Maximum call stack size exceeded
`
After optimization:
`javascript
function factorial(n, acc = 1) {
while (true) {
if (n <= 1) return acc;
let _n_ = n - 1;
let _acc_ = n * acc;
n = _n_;
acc = _acc_;
continue;
}
}
factorial(10000); // โ
Works! Returns Infinity (BigInt for exact result)
`
#### 1. Array Sum
`javascript
function sum(arr, index = 0, acc = 0) {
if (index >= arr.length) return acc;
return sum(arr, index + 1, acc + arr[index]);
}
// Before: Stack overflow at ~10,000 items
// After: Handles millions of items
sum(Array(1000000).fill(1)); // โ
Returns 1000000
`
#### 2. Fibonacci Sequence
`javascript
function fib(n, a = 0, b = 1) {
if (n === 0) return a;
return fib(n - 1, b, a + b);
}
// Before: Stack overflow at ~10,000
// After: Works for any n
fib(10000); // โ
Returns BigInt result
`
#### 3. String Reverse
`javascript
function reverse(str, acc = '') {
if (str.length === 0) return acc;
return reverse(str.slice(1), str[0] + acc);
}
reverse('a'.repeat(100000)); // โ
Works!
`
#### 4. Deep Object Traversal
`javascript${prefix}.${key}
function flatten(obj, prefix = '', acc = {}) {
if (typeof obj !== 'object') {
acc[prefix] = obj;
return acc;
}
for (const key in obj) {
const newKey = prefix ? : key;
flatten(obj[key], newKey, acc);
}
return acc;
}
// Handles deeply nested objects without stack overflow
`
`javascript`
// Also works with arrow functions!
const sum = (n, acc = 0) => {
if (n === 0) return acc;
return sum(n - 1, acc + n);
};
`javascript
// Ternary operators
const countdown = (n, acc = []) =>
n === 0 ? acc : countdown(n - 1, [...acc, n]);
// Multiple conditions
function search(arr, target, index = 0) {
if (index >= arr.length) return -1;
if (arr[index] === target) return index;
return search(arr, target, index + 1);
}
`
| Option | Type | Default | Description |
|--------|------|---------|-------------|
| debug | boolean | false | Enable debug logging during compilation |onlyAnnotated
| | boolean | false | Only optimize functions with annotation comments |annotationTag
| | string | "@tail-recursion" | Custom annotation tag to identify functions for optimization |
When onlyAnnotated is enabled, only functions with the specified annotation will be optimized:
`javascript
/* @tail-recursion /
function factorial(n, acc = 1) {
if (n <= 1) return acc;
return factorial(n - 1, n * acc);
}
// This won't be optimized
function notOptimized(n) {
return n > 0 ? n + notOptimized(n - 1) : 0;
}
`
- Simple tail recursion
- Tail calls in conditional expressions (ternary)
- Tail calls in if/else branches&&
- Tail calls in logical expressions (, ||)
- Arrow functions with tail recursion
- Function expressions assigned to variables
- Non-tail recursive calls (e.g., return n * factorial(n-1))
- Mutual recursion
- Recursion with try/catch blocks
- Functions with both tail and non-tail recursive calls
Tail call optimization can dramatically improve performance and prevent stack overflow errors:
`javascript
// Without optimization: Stack overflow at ~10,000 iterations
// With optimization: Can handle millions of iterations
function sum(n, acc = 0) {
if (n === 0) return acc;
return sum(n - 1, acc + n);
}
sum(1000000); // โ
Works with optimization
`
- Examples - Real-world usage examples
- Contributing Guide - How to contribute
- Benchmark Results - Performance tests
- Project Status - Development progress
Before (Non-Tail):
`javascript`
function factorial(n) {
if (n <= 1) return 1;
return n * factorial(n - 1); // โ Not in tail position
}
After (Tail Recursive):
`javascript`
function factorial(n, acc = 1) {
if (n <= 1) return acc;
return factorial(n - 1, n * acc); // โ
Tail position!
}
The accumulator pattern is key to tail recursion:
`javascript
// Sum with accumulator
function sum(arr, index = 0, acc = 0) {
if (index >= arr.length) return acc;
return sum(arr, index + 1, acc + arr[index]);
}
// Filter with accumulator
function filter(arr, pred, index = 0, acc = []) {
if (index >= arr.length) return acc;
if (pred(arr[index])) {
return filter(arr, pred, index + 1, [...acc, arr[index]]);
}
return filter(arr, pred, index + 1, acc);
}
`
`bashInstall dependencies
npm install
๐งช Testing
`bash
Run all tests
npm testWith coverage
npm test -- --coverageSpecific test file
npm test -- basic.test.ts
`๐งฉ How It Works
1. Detection Phase: The plugin scans the AST for recursive function calls
2. Validation: Ensures all recursive calls are in tail position
3. Transformation: Converts the function body into a
while(true)` loopContributions are welcome! Please feel free to submit a Pull Request.
MIT ยฉ [Your Name]
- GitHub Repository
- Issues
- Babel Plugin Handbook
- babel-plugin-transform-tail-calls - Babel's experimental tail call plugin
- tailcall.js - Runtime tail call optimization
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