From 5615bf6d307b3b99b4b0114ecc86ee8923685e81 Mon Sep 17 00:00:00 2001
From: Brian M Hunt <bmh@tko.io>
Date: Tue, 26 Jun 2018 10:34:36 -0400
Subject: [PATCH] component/jsx)  Support partials in `children`

This would improve substantially with a `trackArrayChanges` on the right observables.
---
 .../spec/componentBindingBehaviors.js         | 42 ++++++++++++-
 packages/tko.utils.jsx/src/jsx.js             | 60 +++++++++++++------
 2 files changed, 82 insertions(+), 20 deletions(-)

diff --git a/packages/tko.binding.component/spec/componentBindingBehaviors.js b/packages/tko.binding.component/spec/componentBindingBehaviors.js
index ab76259a..6aaad161 100644
--- a/packages/tko.binding.component/spec/componentBindingBehaviors.js
+++ b/packages/tko.binding.component/spec/componentBindingBehaviors.js
@@ -894,8 +894,6 @@ describe('Components: Component binding', function () {
     it('inserts a partial when the `template` is an array', function () {
       class ViewModel extends components.ComponentABC {
         static get template () {
-          // Passing <div attr={obs}>{o2}</div> through
-          // babel-plugin-transform-jsx will yield:
           return [
             { elementName: 'b', attributes: { }, children: ['x'] },
             { elementName: 'i', attributes: { }, children: ['y'] },
@@ -907,6 +905,46 @@ describe('Components: Component binding', function () {
       applyBindings(outerViewModel, testNode)
       expect(testNode.children[0].innerHTML).toEqual('<b>x</b><i>y</i><em>z</em>')
     })
+
+    it('inserts partials from `children`', function () {
+      const children = [
+        'abc',
+        { elementName: 'c', attributes: {}, children: [['C']] }
+      ]
+      class ViewModel extends components.ComponentABC {
+        static get template () {
+          return [
+            { elementName: 'b', attributes: { }, children: ['x', children] }
+          ]
+        }
+      }
+      ViewModel.register('test-component')
+      applyBindings(outerViewModel, testNode)
+      expect(testNode.children[0].innerHTML).toEqual('<b>xabc<c>C</c></b>')
+    })
+
+    it('inserts & updates observable partials from `children`', function () {
+      const children = observableArray([
+        'abc',
+        { elementName: 'c', attributes: {}, children: [['C']] }
+      ])
+      class ViewModel extends components.ComponentABC {
+        static get template () {
+          return [
+            { elementName: 'b', attributes: { }, children: ['x', children] }
+          ]
+        }
+      }
+      ViewModel.register('test-component')
+      applyBindings(outerViewModel, testNode)
+      expect(testNode.children[0].innerHTML).toEqual('<b>xabc<c>C</c></b>')
+
+      children.pop()
+      expect(testNode.children[0].innerHTML).toEqual('<b>xabc</b>')
+
+      children.unshift('rrr')
+      expect(testNode.children[0].innerHTML).toEqual('<b>xrrrabc</b>')
+    })
   })
 
   describe('slots', function () {
diff --git a/packages/tko.utils.jsx/src/jsx.js b/packages/tko.utils.jsx/src/jsx.js
index a6788752..d19a3471 100644
--- a/packages/tko.utils.jsx/src/jsx.js
+++ b/packages/tko.utils.jsx/src/jsx.js
@@ -1,6 +1,6 @@
 
 import {
-  cleanNode, removeNode, addDisposeCallback
+  removeNode, addDisposeCallback
 } from 'tko.utils'
 
 import {
@@ -44,8 +44,12 @@ export function jsxToNode (jsx) {
   return node
 }
 
-function appendChild (possibleTemplateElement, nodeToAppend) {
-  if ('content' in possibleTemplateElement) {
+function appendChildOrChildren (possibleTemplateElement, nodeToAppend) {
+  if (Array.isArray(nodeToAppend)) {
+    for (const node of nodeToAppend) {
+      appendChildOrChildren(possibleTemplateElement, node)
+    }
+  } else if ('content' in possibleTemplateElement) {
     possibleTemplateElement.content.appendChild(nodeToAppend)
   } else {
     possibleTemplateElement.appendChild(nodeToAppend)
@@ -69,7 +73,7 @@ function updateChildren (node, children, subscriptions) {
     if (isObservable(child)) {
       subscriptions.push(monitorObservableChild(node, child))
     } else {
-      appendChild(node, convertJsxChildToDom(child))
+      appendChildOrChildren(node, convertJsxChildToDom(child))
     }
   }
 }
@@ -102,28 +106,48 @@ function updateAttributes (node, attributes, subscriptions) {
   }
 }
 
+/**
+ *
+ * @param {jsx} newJsx
+ * @param {HTMLElement|Array} toReplace
+ * @return {HTMLElement|Array} Nodes to replace next time
+ *
+ * TODO: Use trackArrayChanges to minimize changes to the DOM and state-loss.
+ */
+function replaceNodeOrNodes (newJsx, toReplace, parentNode) {
+  const newNodeOrNodes = convertJsxChildToDom(newJsx)
+  const $context = contextFor(toReplace)
+
+  if (Array.isArray(toReplace)) {
+    for (const node of toReplace) { removeNode(node) }
+  } else {
+    removeNode(toReplace)
+  }
+  appendChildOrChildren(parentNode, newNodeOrNodes)
+  if ($context) { applyBindings($context, newNodeOrNodes) }
+  return newNodeOrNodes
+}
+
 function monitorObservableChild (node, child) {
   const jsx = unwrap(child)
-  let nodeToReplace = convertJsxChildToDom(jsx)
+  let toReplace = convertJsxChildToDom(jsx)
+  appendChildOrChildren(node, toReplace)
 
   const subscription = child.subscribe(newJsx => {
-    const newNode = convertJsxChildToDom(newJsx)
-    const $context = contextFor(node)
-    cleanNode(nodeToReplace)
-    node.replaceChild(newNode, nodeToReplace)
-    if ($context) {
-      applyBindings(contextFor(node), newNode)
-    }
-    nodeToReplace = newNode
+    toReplace = replaceNodeOrNodes(newJsx, toReplace, node)
   })
 
-  appendChild(node, nodeToReplace)
   return subscription
 }
 
+/**
+ * Convert a child to the anticipated HTMLElement(s).
+ * @param {string|array|jsx} child
+ * @return {Array|Comment|HTMLElement}
+ */
 function convertJsxChildToDom (child) {
-  return typeof child === 'string'
-    ? document.createTextNode(child)
-    : child ? jsxToNode(child)
-      : document.createComment('[jsx placeholder]')
+  return typeof child === 'string' ? document.createTextNode(child)
+    : Array.isArray(child) ? child.map(convertJsxChildToDom)
+      : child ? jsxToNode(child)
+        : document.createComment('[jsx placeholder]')
 }