Add diff command.

bin/jsonld.js

@@ -8,6 +8,7 @@
  * Copyright (c) 2013-2022 Digital Bazaar, Inc.
  * All rights reserved.
  */
+import {createDeepComparer} from 'deep-comparer';
 import {fileURLToPath} from 'node:url';
 import https from 'node:https';
 import {inspect} from 'node:util';
@@ -424,6 +425,26 @@ _jsonLdCommand(program.command('canonize [filename|URL|-]'))
     await _output(result, cmd);
   });
 
+program.command('diff <filenameA> <filenameB>')
+  .description('compare two JSON-LD documents in expanded form')
+  .action(async function diff(filenameA, filenameB, cmd) {
+    const options = _jsonLdOptions(cmd, filenameA);
+    options.keepFreeFloatingNodes = cmd.keepFreeFloatingNodes;
+
+    const resultA = await jsonld.expand(filenameA, options);
+    const resultB = await jsonld.expand(filenameB, options);
+
+    const deepCompare = createDeepComparer();
+    const differences = await deepCompare(resultA, resultB);
+
+    if(differences.length > 0) {
+      console.log('Differences found:');
+      console.dir(differences, {depth: 5});
+    } else {
+      console.log('No differences found.');
+    }
+  });
+
 program
   .parseAsync(process.argv)
   .catch(e => {

package.json

@@ -33,6 +33,7 @@
   "type": "module",
   "dependencies": {
     "commander": "^11.1.0",
+    "deep-comparer": "^2.0.3",
     "jsonld": "^8.3.2",
     "jsonld-request": "^2.0.1"
   },