ai/size-limit
Size Limit
size-limit is a set of specialized tools for measuring JavaScript bundle sizes and enforcing performance budgets within continuous integration pipelines. It functions as a bundle size monitor and budget enforcer that can reject pull requests when JavaScript bundles exceed predefined size thresholds.
The project distinguishes itself by providing a browser-based execution profiler that calculates the time required to compile and execute JavaScript on simulated low-end hardware. It also includes a tree-shaking validator that analyzes partial import bundle sizes to verify that unused code is correctly removed.
The toolset covers bundle composition analysis to identify the size contribution of internal and external dependencies. It further integrates with CI pipelines to provide automated performance monitoring and feedback loops directly within pull requests.
Features
- Performance Threshold Enforcement - Automatically fails builds when JavaScript bundle sizes exceed predefined quantitative performance thresholds.
- Bundle Composition Analyzers - Decomposes JavaScript bundles to quantify the size contribution of individual internal and external modules.
- Bundle Size Analyzers - Measures the final size of JavaScript bundles and calculates the impact of imported packages.
- Browser Execution Profilers - Calculates the time required to compile and execute JavaScript on simulated low-end hardware via a browser.
- CI/CD Pipeline Integrations - Integrates bundle size monitoring and performance budget checks directly into CI/CD quality workflows.
- Tree-Shaking Validators - Validates tree-shaking effectiveness by measuring bundle size changes when only specific exports are imported.
- Hardware-Constrained Profilers - Simulates low-end device constraints to estimate the real-world performance cost of JavaScript execution.
- Bundle Budgeting - Prevents performance regressions by failing builds when JavaScript bundles exceed a predefined size limit.
- Tree-Shaking Validators - Tests final bundle sizes using partial imports to verify that the bundler correctly removes unused code.
- Tree-Shaking Validators - Verifies that bundlers correctly remove unused code by analyzing partial import bundle sizes.
- Code Dependency Analysis - Extracts and analyzes which external libraries contribute most to the total bundle size.
- Feedback Loops - Posts automated bundle size reports and status checks directly to pull requests to shorten the verification cycle.
- Browser Performance Simulation - Measures the actual time it takes for a browser to compile and execute JavaScript on limited hardware.
- Browser-Based Execution Timing - Calculates the time required to compile and execute JavaScript on simulated low-end hardware using a headless browser.
- Bundle Performance Monitoring - Automatically reports bundle size changes and execution costs within pull requests to maintain application speed.
- Headless Browsers - Uses headless browser engines to measure actual JavaScript compilation and execution time in a controlled environment.
- JavaScript Optimization - Prevents bundle size bloat by setting performance budgets.
- Project Documentation Examples - Features a logo, clear description, and installation steps.
