@jridgewell/trace-mapping 0.3.31: decodedMap

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify @jridgewell/trace-mapping.decodedMap in pkg:npm/%40jridgewell/trace-mapping@0.3.31
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40jridgewell/trace-mapping@0.3.31
Demonstrate these symbols/APIs:
  - @jridgewell/trace-mapping.decodedMap

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:96adf6c0e519ae28ead3ea5e6b838d712e267a7d41a12e84eafba5b6cde31782","contract":["decodedMap returns a DecodedSourceMap object with decoded 2D mappings array from a TraceMap initialized with encoded VLQ string","decodedMap preserves source map metadata including version, file, sources, sourcesContent, names, and sourceRoot","decodedMap correctly decodes 1-segment, 4-segment, and 5-segment mapping tokens","decodedMap works with TraceMap initialized from a JSON string or an already-decoded source map","decodedMap output is a plain object serializable with JSON.stringify and compatible with standard source map consumers","decodedMap preserves ignoreList when present in the source map"],"goal":"verify @jridgewell/trace-mapping.decodedMap in pkg:npm/%40jridgewell/trace-mapping@0.3.31","kind":"HOW","packages":["pkg:npm/%40jridgewell/trace-mapping@0.3.31"],"schemaVersion":1,"symbols":["@jridgewell/trace-mapping.decodedMap"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/%40jridgewell/trace-mapping@0.3.31"],"schemaVersion":1,"subject":"pkg:npm/%40jridgewell/trace-mapping@0.3.31","symbols":["@jridgewell/trace-mapping.decodedMap"],"verifierAdapter":"node-typescript@1"}

import { TraceMap, decodedMap } from '@jridgewell/trace-mapping';

/**
 * Returns a decoded source map object from a source map input (object, JSON string, or TraceMap instance).
 * @param {import('@jridgewell/trace-mapping').SourceMapInput | TraceMap} input
 * @returns {import('@jridgewell/trace-mapping').DecodedSourceMap}
 */
export function getDecodedMap(input) {
  const tracer = input instanceof TraceMap ? input : new TraceMap(input);
  return decodedMap(tracer);
}

export { TraceMap, decodedMap };
export default getDecodedMap;

{
  "name": "sample-trace-mapping-decoded-map",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-trace-mapping-decoded-map",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "@jridgewell/trace-mapping": "0.3.31"
      }
    },
    "node_modules/@jridgewell/resolve-uri": {
      "version": "3.1.2",
      "resolved": "https://registry.npmjs.org/@jridgewell/resolve-uri/-/resolve-uri-3.1.2.tgz",
      "integrity": "sha512-bRISgCIjP20/tbWSPWMEi54QVPRZExkuD9lJL+UIxUKtwVJA8wW1Trb1jMs1RFXo1CBTNZ/5hpC9QvmKWdopKw==",
      "license": "MIT",
      "engines": {
        "node": ">=6.0.0"
      }
    },
    "node_modules/@jridgewell/sourcemap-codec": {
      "version": "1.5.5",
      "resolved": "https://registry.npmjs.org/@jridgewell/sourcemap-codec/-/sourcemap-codec-1.5.5.tgz",
      "integrity": "sha512-cYQ9310grqxueWbl+WuIUIaiUaDcj7WOq5fVhEljNVgRfOUhY9fy2zTvfoqWsnebh8Sl70VScFbICvJnLKB0Og==",
      "license": "MIT"
    },
    "node_modules/@jridgewell/trace-mapping": {
      "version": "0.3.31",
      "resolved": "https://registry.npmjs.org/@jridgewell/trace-mapping/-/trace-mapping-0.3.31.tgz",
      "integrity": "sha512-zzNR+SdQSDJzc8joaeP8QQoCQr8NuYx2dIIytl1QeBEZHJ9uW6hebsrYgbz8hJwUQao3TWCMtmfV8Nu1twOLAw==",
      "license": "MIT",
      "dependencies": {
        "@jridgewell/resolve-uri": "^3.1.0",
        "@jridgewell/sourcemap-codec": "^1.4.14"
      }
    }
  }
}

{
  "name": "sample-trace-mapping-decoded-map",
  "version": "1.0.0",
  "type": "module",
  "main": "index.js",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "@jridgewell/trace-mapping": "0.3.31"
  },
  "license": "MIT-0"
}

{
  "schemaVersion": 1,
  "goal": "verify @jridgewell/trace-mapping.decodedMap in pkg:npm/%40jridgewell/trace-mapping@0.3.31",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40jridgewell/trace-mapping@0.3.31"
  ],
  "symbols": [
    "@jridgewell/trace-mapping.decodedMap"
  ]
}

import assert from 'node:assert/strict';
import { TraceMap, decodedMap, getDecodedMap } from '../index.js';

// 1. decodedMap returns a DecodedSourceMap object with decoded 2D mappings array from a TraceMap initialized with encoded VLQ string
{
  const encodedMap = {
    version: 3,
    file: 'bundle.js',
    sources: ['src/app.js'],
    sourcesContent: ['console.log("hello");'],
    names: ['console', 'log'],
    mappings: 'AAAA,SAASA,GAAG',
    sourceRoot: 'http://example.com/'
  };

  const tracer = new TraceMap(encodedMap);
  const result = decodedMap(tracer);

  assert.equal(typeof result, 'object');
  assert.ok(Array.isArray(result.mappings));
  assert.equal(result.mappings.length, 1);
  assert.ok(result.mappings[0].length >= 1);
  assert.ok(Array.isArray(result.mappings[0][0]));
}

// 2. decodedMap preserves source map metadata including version, file, sources, sourcesContent, names, and sourceRoot
{
  const mapData = {
    version: 3,
    file: 'output.min.js',
    sources: ['module.js', 'helper.js'],
    sourcesContent: ['const a = 1;', 'const b = 2;'],
    names: ['a', 'b'],
    mappings: 'AAAA;ACAA',
    sourceRoot: 'http://example.com/project/'
  };

  const tracer = new TraceMap(mapData);
  const result = decodedMap(tracer);

  assert.equal(result.version, 3);
  assert.equal(result.file, 'output.min.js');
  assert.deepEqual(result.sources, ['module.js', 'helper.js']);
  assert.deepEqual(result.sourcesContent, ['const a = 1;', 'const b = 2;']);
  assert.deepEqual(result.names, ['a', 'b']);
  assert.equal(result.sourceRoot, 'http://example.com/project/');
}

// 3. decodedMap correctly decodes 1-segment, 4-segment, and 5-segment mapping tokens
{
  const mapData = {
    version: 3,
    sources: ['orig.js'],
    names: ['myVar'],
    mappings: 'A;AAAA;AAAAA'
  };

  const tracer = new TraceMap(mapData);
  const result = decodedMap(tracer);

  assert.equal(result.mappings.length, 3);
  assert.deepEqual(result.mappings[0][0], [0]);
  assert.deepEqual(result.mappings[1][0], [0, 0, 0, 0]);
  assert.deepEqual(result.mappings[2][0], [0, 0, 0, 0, 0]);
}

// 4. decodedMap works with TraceMap initialized from a JSON string or an already-decoded source map
{
  const rawDecoded = {
    version: 3,
    file: 'test.js',
    sources: ['test.ts'],
    names: [],
    mappings: [
      [[0, 0, 0, 0]],
      [[4, 0, 1, 2]]
    ]
  };

  const tracerFromDecoded = new TraceMap(rawDecoded);
  const result1 = decodedMap(tracerFromDecoded);
  assert.deepEqual(result1.mappings, [
    [[0, 0, 0, 0]],
    [[4, 0, 1, 2]]
  ]);

  const jsonStr = JSON.stringify(rawDecoded);
  const tracerFromJson = new TraceMap(jsonStr);
  const result2 = decodedMap(tracerFromJson);
  assert.deepEqual(result2.mappings, [
    [[0, 0, 0, 0]],
    [[4, 0, 1, 2]]
  ]);

  const wrapperResult = getDecodedMap(rawDecoded);
  assert.deepEqual(wrapperResult.mappings, result1.mappings);
}

// 5. decodedMap output is a plain object serializable with JSON.stringify and compatible with standard source map consumers
{
  const mapData = {
    version: 3,
    file: 'lib.js',
    sources: ['lib.ts'],
    names: ['func'],
    mappings: 'AAAAA'
  };

  const tracer = new TraceMap(mapData);
  const result = decodedMap(tracer);
  const json = JSON.stringify(result);
  const parsed = JSON.parse(json);

  assert.equal(parsed.version, 3);
  assert.equal(parsed.file, 'lib.js');
  assert.deepEqual(parsed.mappings, [[[0, 0, 0, 0, 0]]]);
}

// 6. decodedMap preserves ignoreList when present in the source map
{
  const mapDataWithIgnore = {
    version: 3,
    sources: ['node_modules/lib.js', 'src/index.js'],
    mappings: 'AAAA;AAAA',
    ignoreList: [0]
  };

  const tracer = new TraceMap(mapDataWithIgnore);
  const result = decodedMap(tracer);

  assert.deepEqual(result.ignoreList, [0]);
}

console.log('Contract tests passed successfully.');