@srcmap/source-map

Drop-in replacement for Mozilla's source-map v0.6 API powered by Rust via WebAssembly.

Same SourceMapConsumer and SourceMapGenerator classes, same behavior. Swap the import and get source map operations backed by Rust under the hood.

Install

npm install @srcmap/source-map

Usage

Consumer

// Before:
// import { SourceMapConsumer } from 'source-map'

// After:
import { SourceMapConsumer } from '@srcmap/source-map'

const consumer = new SourceMapConsumer(sourceMapJsonOrObject)

const pos = consumer.originalPositionFor({ line: 43, column: 10 })
// { source: 'src/app.ts', line: 11, column: 4, name: 'handleClick' }

const content = consumer.sourceContentFor('src/app.ts')

consumer.eachMapping((mapping) => {
  console.log(mapping.generatedLine, mapping.generatedColumn)
})

// Cleanup WASM memory
consumer.destroy()

Generator

import { SourceMapGenerator } from '@srcmap/source-map'

const generator = new SourceMapGenerator({ file: 'bundle.js' })

generator.addMapping({
  generated: { line: 1, column: 0 },
  source: 'src/app.ts',
  original: { line: 10, column: 4 },
  name: 'handleClick',
})

generator.setSourceContent('src/app.ts', sourceCode)

const json = generator.toJSON()
const str = generator.toString()

generator.destroy()

API compatibility

SourceMapConsumer

| Method / Property | Description | |--------|-------------| | originalPositionFor(needle) | Forward lookup (1-based lines, 0-based columns) | | generatedPositionFor(needle) | Reverse lookup | | eachMapping(callback) | Iterate all mappings in generated order | | sourceContentFor(source) | Get source content for a file | | sources | Resolved source file URLs | | sourcesContent | Inline source contents | | file | Output filename | | sourceRoot | Source root prefix | | destroy() | Free WASM resources | | GREATEST_LOWER_BOUND / LEAST_UPPER_BOUND | Search bias constants |

SourceMapGenerator

| Method | Description | |--------|-------------| | addMapping(mapping) | Add a mapping (object-based API) | | setSourceContent(source, content) | Set source content for a file | | applySourceMap(consumer, source?, path?) | Apply a consumer's mappings to this generator | | toJSON() | Return as parsed source map object | | toString() | Return as JSON string | | destroy() | Free WASM resources |

Differences from Mozilla source-map

• Synchronous API: No SourceMapConsumer.with() or promise-based initialization — construction is synchronous
• WASM memory: Call consumer.destroy() / generator.destroy() when done to free WASM memory
• Indexed source maps: Handled natively by the WASM engine

Part of srcmap

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

• @srcmap/trace-mapping - Drop-in for @jridgewell/trace-mapping
• @srcmap/gen-mapping - Drop-in for @jridgewell/gen-mapping
• @srcmap/sourcemap-wasm - Lower-level WASM API (0-based lines)

License

MIT