fix circular json on data routes

Author: nickreese

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@elderjs/elderjs",
-  "version": "1.7.3",
+  "version": "1.7.4",
   "main": "./build/index.js",
   "types": "./build/index.d.ts",
   "engineStrict": true,

src/routes/prepareRouter.ts

@@ -4,6 +4,7 @@ import get from 'lodash.get';
 import Page from '../utils/Page';
 import { RequestOptions, ServerOptions } from '../utils/types';
 import { RouteOptions } from './types';
+import fixCircularJson from '../utils/fixCircularJson';
 
 export function extractDynamicRouteParams({ path, $$meta }) {
   let i = 0;
@@ -175,13 +176,13 @@ function prepareRouter(Elder) {
 
     if (type === 'data' && data) {
       res.setHeader('Content-Type', 'application/json');
-      res.end(JSON.stringify(data));
+      res.end(JSON.stringify(fixCircularJson(data)));
       return undefined;
     }
 
     if (type === 'allRequests' && allRequests) {
       res.setHeader('Content-Type', 'application/json');
-      res.end(JSON.stringify(allRequests));
+      res.end(JSON.stringify(fixCircularJson(allRequests)));
       return undefined;
     }
 

src/utils/__tests__/replaceCircular.spec.ts

@@ -0,0 +1,11 @@
+import fixCircularJson from '../fixCircularJson';
+
+describe('#fixCircularJson', () => {
+  it('Handles circular', () => {
+    const one = { f: 'this-should-work', b: undefined };
+    const two = { h: 123, one };
+    one.b = two;
+
+    expect(JSON.stringify(fixCircularJson(one))).toBe('{"f":"this-should-work","b":{"h":123,"one":"[Circular]"}}');
+  });
+});

src/utils/fixCircularJson.ts

@@ -0,0 +1,20 @@
+function fixCircularJson(val, cache = undefined) {
+  cache = cache || new WeakSet();
+
+  if (val && typeof val === 'object') {
+    if (cache.has(val)) return '[Circular]';
+
+    cache.add(val);
+
+    const obj = Array.isArray(val) ? [] : {};
+    for (const idx of Object.keys(val)) {
+      obj[idx] = fixCircularJson(val[idx], cache);
+    }
+
+    cache.delete(val);
+    return obj;
+  }
+
+  return val;
+}
+export default fixCircularJson;