1 files changed, 75 insertions, 0 deletions
diff --git a/preact/src/render.js b/preact/src/render.js
new file mode 100644
index 0000000..c8ef828
--- /dev/null
+++ b/preact/src/render.js
@@ -0,0 +1,75 @@
+import { EMPTY_OBJ } from './constants';
+import { commitRoot, diff } from './diff/index';
+import { createElement, Fragment } from './create-element';
+import options from './options';
+import { slice } from './util';
+
+/**
+ * Render a Preact virtual node into a DOM element
+ * @param {import('./internal').ComponentChild} vnode The virtual node to render
+ * @param {import('./internal').PreactElement} parentDom The DOM element to
+ * render into
+ * @param {import('./internal').PreactElement | object} [replaceNode] Optional: Attempt to re-use an
+ * existing DOM tree rooted at `replaceNode`
+ */
+export function render(vnode, parentDom, replaceNode) {
+	if (options._root) options._root(vnode, parentDom);
+
+	// We abuse the `replaceNode` parameter in `hydrate()` to signal if we are in
+	// hydration mode or not by passing the `hydrate` function instead of a DOM
+	// element..
+	let isHydrating = typeof replaceNode === 'function';
+
+	// To be able to support calling `render()` multiple times on the same
+	// DOM node, we need to obtain a reference to the previous tree. We do
+	// this by assigning a new `_children` property to DOM nodes which points
+	// to the last rendered tree. By default this property is not present, which
+	// means that we are mounting a new tree for the first time.
+	let oldVNode = isHydrating
+		? null
+		: (replaceNode && replaceNode._children) || parentDom._children;
+
+	vnode = (
+		(!isHydrating && replaceNode) ||
+		parentDom
+	)._children = createElement(Fragment, null, [vnode]);
+
+	// List of effects that need to be called after diffing.
+	let commitQueue = [];
+	diff(
+		parentDom,
+		// Determine the new vnode tree and store it on the DOM element on
+		// our custom `_children` property.
+		vnode,
+		oldVNode || EMPTY_OBJ,
+		EMPTY_OBJ,
+		parentDom.ownerSVGElement !== undefined,
+		!isHydrating && replaceNode
+			? [replaceNode]
+			: oldVNode
+			? null
+			: parentDom.firstChild
+			? slice.call(parentDom.childNodes)
+			: null,
+		commitQueue,
+		!isHydrating && replaceNode
+			? replaceNode
+			: oldVNode
+			? oldVNode._dom
+			: parentDom.firstChild,
+		isHydrating
+	);
+
+	// Flush all queued effects
+	commitRoot(commitQueue, vnode);
+}
+
+/**
+ * Update an existing DOM element with data from a Preact virtual node
+ * @param {import('./internal').ComponentChild} vnode The virtual node to render
+ * @param {import('./internal').PreactElement} parentDom The DOM element to
+ * update
+ */
+export function hydrate(vnode, parentDom) {
+	render(vnode, parentDom, hydrate);
+}