subsetchecksum

Build a deterministic SHA-256 checksum from a subset of object values.

Behavior

• If object is null, returns null.
• keys can be:
  • an array of dot-paths (['profile.name', 'email'])
  • a mapping object ({ 'profile.name': 'name', emailaddress: 'email' })
• If keys is empty (or not provided), key paths are auto-generated from object leaf paths.
• Nested fields are supported with dot-path notation like profile.name.first.
• If a selected value is an object, it is stored as a deterministic JSON string (recursively key-sorted before JSON.stringify).
• If JSON.stringify throws (for example circular references), that subset value is set to null.
• The generated subset object is sorted by key before hashing.
• In mapping-object mode, missing source paths are skipped (they do not write null into the output key).

Install

npm install subsetchecksum

Test

npm test

Usage

const subsetChecksum = require('./index');

const source = {
  id: 5,
  profile: {
    name: 'Dana',
  },
};

const checksum = subsetChecksum(source, ['profile.name', 'id']);
console.log(checksum);

When installed from npm:

const subsetChecksum = require('subsetchecksum');

Mapping Mode Example

const subsetChecksum = require('./index');

const source = {
  fullname: 'Jack Smith',
  emailaddress: '[email protected]',
};

const checksum = subsetChecksum(source, {
  formalname: 'name',
  fullname: 'name',
  emailaddress: 'email',
});

console.log(checksum);