diff()

function diff(
  fromXml: string,
  toXml: string,
  options?: DiffOptions,
): DiffResult

Parses and semantically diffs two DMN XML strings.

Parameters

Name	Type	Description
fromXml	string	XML content of the "before" file
toXml	string	XML content of the "after" file
options	DiffOptions	Optional metadata

DiffOptions

interface DiffOptions {
  fromFile?: string  // shown in meta and renderer headers
  toFile?: string
}

Returns

DiffResult — a structured object containing the summary, metadata, and list of changes.

Example

import { diff } from '@veridtools/dmn-diff'

const result = diff(beforeXml, afterXml, {
  fromFile: 'v1.dmn',
  toFile:   'v2.dmn',
})

console.log(result.meta.hasChanges)       // boolean
console.log(result.summary.modified)      // number
console.log(result.changes.length)        // total number of changes

Algorithm

1. Preprocess — remove BOM, expand CDATA to XML entities
2. Parse — convert XML to a JavaScript object tree (namespace prefixes stripped)
3. Normalize — apply defaults (hitPolicy, isCollection, preferredOrientation), trim whitespace, remove DMNDI
4. Index — build Map<id, element> by traversing the entire tree
5. Diff — for every ID in either model: added / removed / modified (with field-level comparison)
6. LCS fallback — for unindexed elements (rules, bindings, contextEntries without IDs)