@srcmap/remapping

Drop-in replacement for @jridgewell/remapping and @ampproject/remapping powered by Rust via WebAssembly.

Same API, same types, same behavior. Swap the import and get source map composition backed by Rust under the hood.

Install

npm install @srcmap/remapping

Usage

// Before:
// import remapping from '@jridgewell/remapping'
// import remapping from '@ampproject/remapping'

// After:
import remapping from '@srcmap/remapping'

// Remap a single source map through a loader
const composed = remapping(minifiedMap, (sourcefile) => {
  // Return the upstream source map for this file, or null
  return upstreamMaps[sourcefile] ?? null
})

console.log(composed.sources)    // Original sources
console.log(composed.mappings)   // Composed VLQ mappings
console.log(composed.toString()) // JSON string

Compose an array of source maps

// When you have the full chain: [minified map, intermediate map, original map]
const composed = remapping([minifiedMap, intermediateMap], (sourcefile) => {
  return upstreamMaps[sourcefile] ?? null
})

Options

const composed = remapping(minifiedMap, loader, {
  excludeContent: true, // Omit sourcesContent from the output
})

API compatibility

| Export | Description | |--------|-------------| | remapping(input, loader, options?) | Remap a single source map through a loader | | remapping(inputs[], loader, options?) | Compose an array of source maps | | SourceMap | Result class with version, file, mappings, sources, sourcesContent, names, ignoreList |

The loader function receives a source filename and should return the upstream source map (as a JSON string, parsed object, or decoded source map), or null if no upstream map exists.

SourceMap result

| Property / Method | Type | Description | |--------|------|-------------| | version | number | Source map version (always 3) | | file | string \| undefined | Output filename | | mappings | string | VLQ-encoded mappings | | sources | (string \| null)[] | Source filenames | | sourcesContent | (string \| null)[] \| undefined | Inline source contents | | names | string[] | Name strings | | ignoreList | number[] \| undefined | Indices of ignored sources | | toString() | string | Serialize as JSON string | | toJSON() | RawSourceMap | Return as parsed object |

Differences from @jridgewell/remapping

• WASM-powered: Composition runs in Rust via WebAssembly
• Indexed source maps: Handled natively (no JS-side flattening)

Part of srcmap

High-performance source map tooling written in Rust. See also:

• @srcmap/trace-mapping - Drop-in for @jridgewell/trace-mapping (consumer)
• @srcmap/gen-mapping - Drop-in for @jridgewell/gen-mapping (generator)
• @srcmap/remapping-wasm - Lower-level WASM remapping API

License

MIT