source-map-js 1.2.1: SourceMapConsumer

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 source-map-js.SourceMapConsumer in pkg:npm/source-map-js@1.2.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/source-map-js@1.2.1
Demonstrate these symbols/APIs:
  - source-map-js.SourceMapConsumer

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:e6b64c853b8effa53d4b325a434b8639a325d133003e39f614c88e22621d38b1","contract":["assert SourceMapConsumer initializes from raw source map object and parses file and sources","assert SourceMapConsumer resolves original position and symbol name for generated coordinates","assert SourceMapConsumer applies GREATEST_LOWER_BOUND and LEAST_UPPER_BOUND bias for unmapped column queries","assert SourceMapConsumer resolves generated position and all generated positions for original coordinate","assert SourceMapConsumer retrieves embedded source content and validates source completeness","assert SourceMapConsumer iterates mappings sequentially via eachMapping"],"goal":"verify source-map-js.SourceMapConsumer in pkg:npm/source-map-js@1.2.1","kind":"HOW","packages":["pkg:npm/source-map-js@1.2.1"],"schemaVersion":1,"symbols":["source-map-js.SourceMapConsumer"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/source-map-js@1.2.1"],"schemaVersion":1,"subject":"pkg:npm/source-map-js@1.2.1","symbols":["source-map-js.SourceMapConsumer"],"verifierAdapter":"node-typescript@1"}

const { SourceMapConsumer } = require('source-map-js');

/**
 * Creates a SourceMapConsumer instance from a raw source map object or JSON string.
 *
 * @param {Object|string} rawSourceMap - Raw source map object or JSON string.
 * @returns {SourceMapConsumer}
 */
function createConsumer(rawSourceMap) {
  return new SourceMapConsumer(rawSourceMap);
}

/**
 * Resolves original position for a generated coordinate.
 *
 * @param {SourceMapConsumer} consumer - The consumer instance.
 * @param {number} line - Generated line number (1-based).
 * @param {number} column - Generated column number (0-based).
 * @param {number} [bias] - Bias (GREATEST_LOWER_BOUND or LEAST_UPPER_BOUND).
 * @returns {{ source: string|null, line: number|null, column: number|null, name: string|null }}
 */
function resolveOriginalPosition(consumer, line, column, bias) {
  const query = { line, column };
  if (bias !== undefined) {
    query.bias = bias;
  }
  return consumer.originalPositionFor(query);
}

/**
 * Resolves generated position for an original source coordinate.
 *
 * @param {SourceMapConsumer} consumer - The consumer instance.
 * @param {string} source - Source file path.
 * @param {number} line - Original line number (1-based).
 * @param {number} column - Original column number (0-based).
 * @returns {{ line: number|null, column: number|null, lastColumn: number|null }}
 */
function resolveGeneratedPosition(consumer, source, line, column) {
  return consumer.generatedPositionFor({ source, line, column });
}

module.exports = {
  SourceMapConsumer,
  createConsumer,
  resolveOriginalPosition,
  resolveGeneratedPosition,
};

{
  "name": "sample-source-map-js-consumer",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-source-map-js-consumer",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "source-map-js": "1.2.1"
      }
    },
    "node_modules/source-map-js": {
      "version": "1.2.1",
      "resolved": "https://registry.npmjs.org/source-map-js/-/source-map-js-1.2.1.tgz",
      "integrity": "sha512-UXWMKhLOwVKb728IUtQPXxfYU+usdybtUrK/8uGE8CQMvrhOpwvzDBwj0QhSL7MQc7vIsISBG8VQ8+IDQxpfQA==",
      "license": "BSD-3-Clause",
      "engines": {
        "node": ">=0.10.0"
      }
    }
  }
}

{
  "name": "sample-source-map-js-consumer",
  "version": "1.0.0",
  "description": "Clean-room sample verifying source-map-js.SourceMapConsumer in pkg:npm/source-map-js@1.2.1",
  "main": "index.js",
  "license": "MIT-0",
  "dependencies": {
    "source-map-js": "1.2.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify source-map-js.SourceMapConsumer in pkg:npm/source-map-js@1.2.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/source-map-js@1.2.1"
  ],
  "symbols": [
    "source-map-js.SourceMapConsumer"
  ]
}

import assert from 'node:assert';
import sourceMapJs from 'source-map-js';
const { SourceMapConsumer } = sourceMapJs;
import {
  createConsumer,
  resolveOriginalPosition,
  resolveGeneratedPosition
} from '../index.js';

// Pre-computed valid v3 source map:
// Source file: "src/math.js"
// Original lines:
//   line 1: export function add(a, b) {
//   line 2:   return a + b;
//   line 3: }
// Generated file: "dist/bundle.js"
// Mappings:
//   gen line 1, col 0  -> src/math.js line 1, col 0, symbol 'add'
//   gen line 1, col 10 -> src/math.js line 2, col 2
//   gen line 1, col 20 -> src/math.js line 2, col 9
const rawMap = {
  version: 3,
  sources: ['src/math.js'],
  names: ['add'],
  mappings: 'AAAAA,UACE,UAAO',
  file: 'dist/bundle.js',
  sourceRoot: 'http://example.com/project/',
  sourcesContent: ['export function add(a, b) {\n  return a + b;\n}\n']
};

// 1. assert SourceMapConsumer initializes from raw source map object and parses file and sources
const consumer = createConsumer(rawMap);
assert.ok(consumer instanceof SourceMapConsumer, 'createConsumer returns a SourceMapConsumer instance');
assert.strictEqual(consumer.file, 'dist/bundle.js', 'consumer parses file property');
assert.strictEqual(consumer.sourceRoot, 'http://example.com/project/', 'consumer parses sourceRoot property');
assert.deepStrictEqual(
  consumer.sources,
  ['http://example.com/project/src/math.js'],
  'consumer prepends sourceRoot to sources'
);

// 2. assert SourceMapConsumer resolves original position and symbol name for generated coordinates
const pos1 = resolveOriginalPosition(consumer, 1, 0);
assert.strictEqual(pos1.source, 'http://example.com/project/src/math.js', 'resolves source path for mapping');
assert.strictEqual(pos1.line, 1, 'resolves original line');
assert.strictEqual(pos1.column, 0, 'resolves original column');
assert.strictEqual(pos1.name, 'add', 'resolves mapped identifier name');

const pos2 = resolveOriginalPosition(consumer, 1, 10);
assert.strictEqual(pos2.source, 'http://example.com/project/src/math.js', 'resolves source for second mapping');
assert.strictEqual(pos2.line, 2, 'resolves line 2');
assert.strictEqual(pos2.column, 2, 'resolves column 2');
assert.strictEqual(pos2.name, null, 'returns null name for mapping without identifier');

// 3. assert SourceMapConsumer applies GREATEST_LOWER_BOUND and LEAST_UPPER_BOUND bias for unmapped column queries
const lowerPos = resolveOriginalPosition(
  consumer,
  1,
  15,
  SourceMapConsumer.GREATEST_LOWER_BOUND
);
assert.strictEqual(lowerPos.line, 2, 'lower bound resolves previous mapping line');
assert.strictEqual(lowerPos.column, 2, 'lower bound resolves previous mapping column');

const upperPos = resolveOriginalPosition(
  consumer,
  1,
  15,
  SourceMapConsumer.LEAST_UPPER_BOUND
);
assert.strictEqual(upperPos.line, 2, 'upper bound resolves next mapping line');
assert.strictEqual(upperPos.column, 9, 'upper bound resolves next mapping column');

// 4. assert SourceMapConsumer resolves generated position and all generated positions for original coordinate
const genPos = resolveGeneratedPosition(
  consumer,
  'http://example.com/project/src/math.js',
  2,
  2
);
assert.strictEqual(genPos.line, 1, 'resolves generated line');
assert.strictEqual(genPos.column, 10, 'resolves generated column');

const allGen = consumer.allGeneratedPositionsFor({
  source: 'http://example.com/project/src/math.js',
  line: 2,
  column: 2
});
assert.ok(Array.isArray(allGen), 'allGeneratedPositionsFor returns an array');
assert.strictEqual(allGen.length, 1, 'returns one matching generated position');
assert.strictEqual(allGen[0].line, 1, 'matching generated line');
assert.strictEqual(allGen[0].column, 10, 'matching generated column');

// 5. assert SourceMapConsumer retrieves embedded source content and validates source completeness
assert.strictEqual(consumer.hasContentsOfAllSources(), true, 'hasContentsOfAllSources returns true');
assert.strictEqual(
  consumer.sourceContentFor('src/math.js'),
  'export function add(a, b) {\n  return a + b;\n}\n',
  'retrieves content by relative source path'
);
assert.strictEqual(
  consumer.sourceContentFor('http://example.com/project/src/math.js'),
  'export function add(a, b) {\n  return a + b;\n}\n',
  'retrieves content by full resolved source URL'
);
assert.strictEqual(
  consumer.sourceContentFor('nonexistent.js', true),
  null,
  'returns null for nonexistent source with returnNullOnMissing true'
);

// 6. assert SourceMapConsumer iterates mappings sequentially via eachMapping
const iterated = [];
consumer.eachMapping((m) => {
  iterated.push({
    genLine: m.generatedLine,
    genCol: m.generatedColumn,
    origLine: m.originalLine,
    origCol: m.originalColumn,
    name: m.name
  });
});
assert.strictEqual(iterated.length, 3, 'eachMapping iterates exactly 3 mappings');
assert.deepStrictEqual(
  iterated[0],
  { genLine: 1, genCol: 0, origLine: 1, origCol: 0, name: 'add' },
  'first mapping matches'
);
assert.deepStrictEqual(
  iterated[1],
  { genLine: 1, genCol: 10, origLine: 2, origCol: 2, name: null },
  'second mapping matches'
);
assert.deepStrictEqual(
  iterated[2],
  { genLine: 1, genCol: 20, origLine: 2, origCol: 9, name: null },
  'third mapping matches'
);

console.log('All contract assertions passed.');