Add postpatch hook

README.md

@@ -124,12 +124,13 @@ var vnode = h('div', {style: {color: '#000'}}, [
 #### Overview
 
 | Name        | Triggered when | Arguments to callback |
-| --------- | -------------- | --------------------- |
+| ----------- | -------------- | --------------------- |
 | `pre`       | the patch process begins. | none |
 | `create`    | a DOM element has been created based on a VNode. | `emptyVNode, vnode` |
 | `insert`    | an element has been inserted into the DOM. | `vnode` |
-| `patch`   | an element is about to be patched. | `oldVnode, vnode` |
+| `prepatch`  | an element is about to be patched. | `oldVnode, vnode` |
 | `update`    | an element is being updated. | `oldVnode, vnode` |
+| `postpatch` | an element has been patched. | `oldVnode, vnode` |
 | `remove`    | an element is directly being removed from the DOM. | `vnode, removeCallback` |
 | `destroy`   | an element is being removed from the DOM or it's parent is. | `vnode` |
 | `post`      | the patch process is done. | none |

snabbdom.js

@@ -175,9 +175,9 @@ function init(modules) {
   }
 
   function patchVnode(oldVnode, vnode) {
-    var i;
+    var i, hook;
-    if (!isUndef(i = vnode.data) && !isUndef(i = i.hook) && !isUndef(i = i.patch)) {
+    if (!isUndef(i = vnode.data) && !isUndef(hook = i.hook) && !isUndef(i = hook.prepatch)) {
-      i = i(oldVnode, vnode);
+      i(oldVnode, vnode);
     }
     if (!isUndef(i = oldVnode.data) && !isUndef(i = i.vnode)) oldVnode = i;
     if (!isUndef(i = vnode.data) && !isUndef(i = i.vnode)) vnode = i;
@@ -199,6 +199,9 @@ function init(modules) {
     } else if (oldVnode.text !== vnode.text) {
       elm.textContent = vnode.text;
     }
+    if (!isUndef(hook) && !isUndef(i = hook.postpatch)) {
+      i(oldVnode, vnode);
+    }
     return vnode;
   }
 

test/core.js

@@ -505,7 +505,7 @@ describe('snabbdom', function() {
         patch(vnode0, vnode1);
         assert.equal(1, result.length);
       });
-      it('calls `patch` listener', function() {
+      it('calls `prepatch` listener', function() {
         var result = [];
         function cb(oldVnode, vnode) {
           assert.strictEqual(oldVnode, vnode1.children[1]);
@@ -514,14 +514,14 @@ describe('snabbdom', function() {
         }
         var vnode1 = h('div', [
           h('span', 'First sibling'),
-          h('div', {hook: {patch: cb}}, [
+          h('div', {hook: {prepatch: cb}}, [
             h('span', 'Child 1'),
             h('span', 'Child 2'),
           ]),
         ]);
         var vnode2 = h('div', [
           h('span', 'First sibling'),
-          h('div', {hook: {patch: cb}}, [
+          h('div', {hook: {prepatch: cb}}, [
             h('span', 'Child 1'),
             h('span', 'Child 2'),
           ]),
@@ -530,6 +530,34 @@ describe('snabbdom', function() {
         patch(vnode1, vnode2);
         assert.equal(result.length, 1);
       });
+      it('calls `postpatch` after `prepatch` listener', function() {
+        var pre = [], post = [];
+        function preCb(oldVnode, vnode) {
+          pre.push(pre);
+        }
+        function postCb(oldVnode, vnode) {
+          assert.equal(pre.length, post.length + 1);
+          post.push(post);
+        }
+        var vnode1 = h('div', [
+          h('span', 'First sibling'),
+          h('div', {hook: {prepatch: preCb, postpatch: postCb}}, [
+            h('span', 'Child 1'),
+            h('span', 'Child 2'),
+          ]),
+        ]);
+        var vnode2 = h('div', [
+          h('span', 'First sibling'),
+          h('div', {hook: {prepatch: preCb, postpatch: postCb}}, [
+            h('span', 'Child 1'),
+            h('span', 'Child 2'),
+          ]),
+        ]);
+        patch(vnode0, vnode1);
+        patch(vnode1, vnode2);
+        assert.equal(pre.length, 1);
+        assert.equal(post.length, 1);
+      });
       it('calls `update` listener', function() {
         var result1 = [];
         var result2 = [];

thunk.js

@@ -5,7 +5,7 @@ function init(thunk) {
   cur.vnode = cur.fn.apply(undefined, cur.args);
 }
 
-function patch(oldThunk, thunk) {
+function prepatch(oldThunk, thunk) {
   var i, old = oldThunk.data, cur = thunk.data;
   var oldArgs = old.args, args = cur.args;
   cur.vnode = old.vnode;
@@ -27,7 +27,7 @@ module.exports = function(name, fn /* args */) {
     args[i - 2] = arguments[i];
   }
   return h('thunk' + name, {
-    hook: {init: init, patch: patch},
+    hook: {init: init, prepatch: prepatch},
     fn: fn, args: args,
   });
 };