feat(hiccup): update derefContext() to only apply to selected keys

packages/hiccup/src/deref.ts

@@ -1,14 +1,21 @@
 import { implementsFunction } from "@thi.ng/checks/implements-function";
 
+/**
+ * Takes an arbitrary `ctx` object and array of `keys`. Attempts to call
+ * `.deref()` on all given keys' values and stores result values instead
+ * of original. Returns updated copy of `ctx` or original if `ctx` is
+ * `null` or no keys were given.
+ *
+ * @param ctx
+ * @param keys
+ */
 export const derefContext =
-    (ctx: any) => {
-        if (ctx == null) return ctx;
-        const res = {};
-        for (let k in ctx) {
-            const v = ctx[k];
-            res[k] = implementsFunction(v, "deref") ?
-                v.deref() :
-                v;
+    (ctx: any, keys: PropertyKey[]) => {
+        if (ctx == null || !keys || !keys.length) return ctx;
+        const res = { ...ctx };
+        for (let k of keys) {
+            const v = res[k];
+            implementsFunction(v, "deref") && (res[k] = v.deref());
         }
         return res;
     };

packages/hiccup/src/serialize.ts

@@ -11,7 +11,6 @@ import {
     VOID_TAGS
 } from "./api";
 import { css } from "./css";
-import { derefContext } from "./deref";
 import { escape } from "./escape";
 
 /**
@@ -70,10 +69,10 @@ import { escape } from "./escape";
  * as arguments when that function is called. The return value the
  * function MUST be a valid new tree (or `undefined`).
  *
- * If the `ctx` object is given a shallow copy is passed to component
- * fns and any context keys with values implementing the thi.ng/api
- * `IDeref` interface, will be automatically deref'd prior to
- * serialization.
+ * If the `ctx` object it'll be passed to each embedded component fns.
+ * Optionally call `derefContext()` prior to `serialize()` to
+ * auto-deref context keys with values implementing the thi.ng/api
+ * `IDeref` interface.
  *
  * ```js
  * const foo = (ctx, a, b) => ["div#" + a, ctx.foo, b];
@@ -123,7 +122,7 @@ import { escape } from "./escape";
  * @param keys attach key attribs
  */
 export const serialize = (tree: any, ctx?: any, escape = false, span = false, keys = span, path = [0]) =>
-    _serialize(tree, derefContext(ctx), escape, span, keys, path);
+    _serialize(tree, ctx, escape, span, keys, path);
 
 const _serialize = (tree: any, ctx: any, esc: boolean, span: boolean, keys: boolean, path: any[]) => {
     if (tree == null) {