@jridgewell/trace-mapping 0.3.31: encodedMappings

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.encodedMappings 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.encodedMappings

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:sha256:2b77f0f9cefe2e13b6948dc32c66568cd50400883267a283fc0586ab1b9fff88","contract":["encodedMappings returns the VLQ-encoded string from a TraceMap initialized with an encoded mappings string","encodedMappings encodes a 2D array of decoded mapping segments into a standard VLQ mappings string","encodedMappings preserves empty line semicolons when encoding multi-line mappings","encodedMappings returns an empty string when initialized with empty string mappings or an empty array","encodedMappings returns identical cached string across multiple calls on the same TraceMap instance","getEncodedMappings helper function accepts either a TraceMap instance or raw source map input"],"goal":"verify @jridgewell/trace-mapping.encodedMappings 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.encodedMappings"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"esm","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.encodedMappings"],"verifierAdapter":"node-typescript@1"}

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

/**
 * Returns the VLQ-encoded mappings string from a source map input or TraceMap instance.
 * @param {import('@jridgewell/trace-mapping').SourceMapInput | TraceMap} input
 * @returns {string}
 */
export function getEncodedMappings(input) {
  const tracer = input instanceof TraceMap ? input : new TraceMap(input);
  return encodedMappings(tracer);
}

export { TraceMap, encodedMappings };
export default getEncodedMappings;

{
  "name": "sample-trace-mapping-encoded-mappings",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-trace-mapping-encoded-mappings",
      "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-encoded-mappings",
  "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.encodedMappings in pkg:npm/%40jridgewell/trace-mapping@0.3.31",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40jridgewell/trace-mapping@0.3.31"
  ],
  "symbols": [
    "@jridgewell/trace-mapping.encodedMappings"
  ]
}

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

// 1. encodedMappings returns the VLQ-encoded string from a TraceMap initialized with an encoded mappings string
{
  const encodedMapInput = {
    version: 3,
    file: 'bundle.js',
    sources: ['src/main.js'],
    sourcesContent: ['console.log("hello");'],
    names: ['console', 'log'],
    mappings: 'AAAA,SAASA,GAAG'
  };
  const tracer = new TraceMap(encodedMapInput);
  const result = encodedMappings(tracer);

  assert.equal(typeof result, 'string');
  assert.equal(result, 'AAAA,SAASA,GAAG');
}

// 2. encodedMappings encodes a 2D array of decoded mapping segments into a standard VLQ mappings string
{
  const decodedMapInput = {
    version: 3,
    file: 'bundle.js',
    sources: ['foo.js'],
    sourcesContent: ['function foo() { return 1; }'],
    names: ['foo'],
    mappings: [
      [[0, 0, 0, 0, 0], [10, 0, 0, 9]],
      [[0, 0, 0, 16]]
    ]
  };
  const tracer = new TraceMap(decodedMapInput);
  const result = encodedMappings(tracer);

  assert.equal(typeof result, 'string');
  assert.equal(result, 'AAAAA,UAAS;AAAO');
}

// 3. encodedMappings preserves empty line semicolons when encoding multi-line mappings
{
  const multiLineMap = {
    version: 3,
    sources: ['source.js'],
    names: [],
    mappings: 'AAAA;;AAAA'
  };
  const tracerFromEncoded = new TraceMap(multiLineMap);
  assert.equal(encodedMappings(tracerFromEncoded), 'AAAA;;AAAA');

  const multiLineDecoded = {
    version: 3,
    sources: ['source.js'],
    names: [],
    mappings: [
      [[0, 0, 0, 0]],
      [],
      [[0, 0, 0, 0]]
    ]
  };
  const tracerFromDecoded = new TraceMap(multiLineDecoded);
  assert.equal(encodedMappings(tracerFromDecoded), 'AAAA;;AAAA');
}

// 4. encodedMappings returns an empty string when initialized with empty string mappings or an empty array
{
  const emptyStrMap = {
    version: 3,
    sources: [],
    names: [],
    mappings: ''
  };
  const tracerEmptyStr = new TraceMap(emptyStrMap);
  assert.equal(encodedMappings(tracerEmptyStr), '');

  const emptyArrMap = {
    version: 3,
    sources: [],
    names: [],
    mappings: []
  };
  const tracerEmptyArr = new TraceMap(emptyArrMap);
  assert.equal(encodedMappings(tracerEmptyArr), '');
}

// 5. encodedMappings returns identical cached string across multiple calls on the same TraceMap instance
{
  const mapData = {
    version: 3,
    sources: ['app.js'],
    names: ['greet'],
    mappings: 'AAAA;ACAA'
  };
  const tracer = new TraceMap(mapData);
  const first = encodedMappings(tracer);
  const second = encodedMappings(tracer);

  assert.equal(first, 'AAAA;ACAA');
  assert.equal(first, second);
}

// 6. getEncodedMappings helper function accepts either a TraceMap instance or raw source map input
{
  const rawMap = {
    version: 3,
    sources: ['helper.js'],
    names: [],
    mappings: 'AAAA'
  };
  const fromRaw = getEncodedMappings(rawMap);
  const tracer = new TraceMap(rawMap);
  const fromTracer = getEncodedMappings(tracer);

  assert.equal(fromRaw, 'AAAA');
  assert.equal(fromTracer, 'AAAA');
  assert.equal(fromRaw, fromTracer);
}

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