patcharan

patcharan lets you wrap JavaScript functions with multiple patches and remove them individually — even out of order. Patches are stacked and tracked, so removing one automatically rebuilds the function with the remaining patches intact.

Usage

import { patch, unpatch } from 'patcharan';

const mod = {
  greet(name) {
    return `hello ${name}`;
  }
};

// A patcher receives the original function and returns a replacement
const loud = (orig) => function (...args) {
  return orig.apply(this, args).toUpperCase();
};

patch(mod, 'greet', loud);
mod.greet('world'); // => "HELLO WORLD"

unpatch(mod, 'greet', loud);
mod.greet('world'); // => "hello world"

Stacking patches

Multiple patches can be applied to the same function. When a patch is removed with unpatch, the remaining patches are re-applied in order so the function stays consistent.

const logger = (orig) => function (...args) {
  console.log('called with', args);
  return orig.apply(this, args);
};

const timer = (orig) => function (...args) {
  const start = performance.now();
  const result = orig.apply(this, args);
  console.log(`took ${performance.now() - start}ms`);
  return result;
};

patch(mod, 'greet', logger);
patch(mod, 'greet', timer);

// Remove logger while keeping timer active
unpatch(mod, 'greet', logger);

API Reference