@stackline/inline-source-map

A maintained, typed, inline-source-map-compatible generator for modern Node.js and browser build pipelines.

Docs and playground | npm | GitHub | Migration | Security | Changelog

Current package version: 1.0.1

Why this package?

inline-source-map remains embedded in build tools and transpilers, but its published package still targets an old source-map generator and its upstream test workflow does not exercise modern Node.js releases.

This fork preserves the compact CommonJS API while adding:

• current source-map generation through source-map@0.8;
• CommonJS, Node ESM, TypeScript, and browser-bundle verification;
• TypeScript declarations without changing the JavaScript call shape;
• null-prototype storage for source file names such as __proto__;
• UTF-8 base64 encoding in browsers with no global Buffer;
• reproducible package, compatibility, coverage, and install tests;
• preserved MIT attribution to the original project.

No runtime security advisory is claimed for the upstream package. This fork is about maintained compatibility, modern verification, and defensive defaults.

Compatibility at a glance

Item	Value
Package	@stackline/inline-source-map@1.0.1
API baseline	inline-source-map@0.6.3
Runtime	Node.js 12+, browser bundles
Modules	Callable CommonJS with Node ESM default import
Types	First-party TypeScript declarations
Runtime dependencies	One maintained source-map generator

Installation

Install under the public Stackline name:

npm install @stackline/inline-source-map

Or replace the original package without changing imports:

npm install inline-source-map@npm:@stackline/inline-source-map

Existing CommonJS remains unchanged:

const inlineSourceMap = require('inline-source-map');

Quick start

const inlineSourceMap = require('@stackline/inline-source-map');

const source = [
  'const answer = 42;',
  'console.log(answer);'
].join('\n');

const map = inlineSourceMap({ file: 'bundle.js' })
  .addGeneratedMappings('answer.js', source)
  .addSourceContent('answer.js', source);

const output = source + '\n' + map.inlineMappingUrl();

ESM

Node.js exposes the callable CommonJS export as the default import:

import inlineSourceMap from '@stackline/inline-source-map';

const map = inlineSourceMap().addGeneratedMappings('input.js', 'let x = 1;');

The package intentionally retains one CommonJS implementation instead of shipping divergent ESM and CommonJS code paths.

API

inlineSourceMap(options?)

Creates a Generator. Supported options are file, sourceRoot, and charset. The default charset label is utf-8.

generator.addGeneratedMappings(sourceFile, source, offset?)

Adds an identity mapping for every source line. As in the original package, line and column offsets are applied to every generated mapping.

generator.addMappings(sourceFile, mappings, offset?)

Adds supplied generated/original positions. A mapping without original produces a generated-only source-map segment.

generator.addSourceContent(sourceFile, sourceContent)

Embeds source text. File names are stored in a null-prototype dictionary, so special JavaScript object names are handled as ordinary source names.

Output methods

• toJSON() returns the version 3 source-map object;
• toString() returns its compact JSON representation;
• base64Encode() returns the UTF-8 JSON as base64;
• inlineMappingUrl() returns the complete //# sourceMappingURL=... comment;
• gen() returns the underlying SourceMapGenerator.

_mappings() is retained for compatibility and returns a diagnostic snapshot. Code should prefer toJSON() because underscore-prefixed internals are not a stable extension point in the underlying source-map project.

TypeScript

The package includes declarations for the callable export and Generator:

import inlineSourceMap = require('@stackline/inline-source-map');

const generator: inlineSourceMap.Generator = inlineSourceMap({
  file: 'bundle.js'
});

Browser bundles

Bundle the package with Browserify, esbuild, Rollup, Vite, or webpack. The package's browser field selects a prebuilt CommonJS entry that contains only the generator path and uses the browser's global URL. The base64 path uses Buffer when available and standard TextEncoder plus btoa in browsers. No browser global is installed by the package.

Compatibility

The JavaScript runtime supports Node.js 12 and newer. Development tooling uses Node.js 20.19 or newer. See COMPATIBILITY_CONTRACT.md for the exact preserved behaviors and MIGRATION.md for alias installation.

Release evidence

The release gate verifies:

• 14 focused regression tests;
• five differential compatibility scenarios against inline-source-map@0.6.3;
• 100% line, statement, and function coverage;
• Node.js 12, 14, 16, 18, 20, 22, and 24;
• TypeScript 3.9, 4.7, 4.9, 5.9, 6.0, and 7.0;
• CommonJS, ESM, browser, packed install, publint, and type export checks.

The interactive documentation playground runs the production browser bundle and exposes the generated Source Map v3 JSON.

Trust and maintenance

• Every release is built from the public repository.
• CI validates runtime compatibility, types, package exports, and clean installs.
• Security reports use the private process in SECURITY.md.
• License and upstream attribution remain in LICENSE, NOTICE, and THIRD_PARTY_LICENSES.md.

Provenance

This is an independent maintained fork of Thorsten Lorenz's MIT-licensed inline-source-map. The original copyright and license text are preserved in LICENSE, with additional attribution in NOTICE.