gorhill
diff --git a/‎src/js/jsonpath.js
Lines changed: 19 additions & 2 deletions b/‎src/js/jsonpath.js
Lines changed: 19 additions & 2 deletions
@@ -99,6 +99,10 @@ export class JSONPath {
         const r = this.#compile(query, 0);
         if ( r === undefined ) { return; }
         if ( r.i !== query.length ) {
+            if ( query.startsWith('+=', r.i) ) {
+                r.modify = '+';
+                r.i += 1;
+            }
             if ( query.startsWith('=', r.i) === false ) { return; }
             try { r.rval = JSON.parse(query.slice(r.i+1)); }
             catch { return; }
@@ -114,15 +118,19 @@ export class JSONPath {
     }
     apply(root) {
         if ( this.valid === false ) { return 0; }
-        const { rval } = this.#compiled;
+        const { modify, rval } = this.#compiled;
         this.#root = root;
         const paths = this.#evaluate(this.#compiled.steps, []);
         const n = paths.length;
         let i = n;
         while ( i-- ) {
             const { obj, key } = this.#resolvePath(paths[i]);
             if ( rval !== undefined ) {
-                obj[key] = rval;
+                if ( modify === '+' ) {
+                    this.#modifyVal(obj, key, rval);
+                } else {
+                    obj[key] = rval;
+                }
             } else if ( Array.isArray(obj) && typeof key === 'number' ) {
                 obj.splice(key, 1);
             } else {
@@ -450,4 +458,13 @@ export class JSONPath {
         }
         if ( outcome ) { return k; }
     }
+    #modifyVal(obj, key, rval) {
+        const lval = obj[key];
+        if ( rval instanceof Object === false ) { return; }
+        if ( lval instanceof Object === false ) { return; }
+        if ( Array.isArray(lval) ) { return; }
+        for ( const [ k, v ] of Object.entries(rval) ) {
+            lval[k] = v;
+        }
+    }
 }