recycling => shouldRecycle, Fix #1992 (#1993)

* Fix #1992

* doc in changelog

* add test for #1992

docs/change-log.md

@@ -40,6 +40,7 @@
 - API: Event handlers, when set to literally `undefined` (or any non-function), are now correctly removed.
 - core: `xlink:href` attributes are now correctly removed
 - core: render() function can no longer prevent from changing `document.activeElement` in lifecycle hooks
+- render: fixed an ommission that caused `oninit` to be called unnecessarily in some cases [#1992](https://github.com/MithrilJS/mithril.js/issues/1992)
 
 ---
 

render/render.js

@@ -235,7 +235,7 @@ module.exports = function($window) {
 						if (oldIndex != null) {
 							var movable = old[oldIndex]
 							var shouldRecycle = (pool != null && oldIndex >= old.length - pool.length) || ((pool == null) && recycling)
-							updateNode(parent, movable, v, hooks, getNextSibling(old, oldEnd + 1, nextSibling), recycling, ns)
+							updateNode(parent, movable, v, hooks, getNextSibling(old, oldEnd + 1, nextSibling), shouldRecycle, ns)
 							insertNode(parent, toFragment(movable), nextSibling)
 							old[oldIndex].skip = true
 							if (movable.dom != null) nextSibling = movable.dom

render/tests/test-oninit.js

@@ -199,4 +199,27 @@ o.spec("oninit", function() {
 		o(vnode.dom.oninit).equals(undefined)
 		o(vnode.dom.attributes["oninit"]).equals(undefined)
 	})
+	
+	o("No spurious oninit calls in mapped keyed diff when the pool is involved (#1992)", function () {
+		var oninit1 = o.spy()
+		var oninit2 = o.spy()
+		var oninit3 = o.spy()
+
+		render(root, [
+			{tag: "p", key: 1, attrs: {oninit: oninit1}},
+			{tag: "p", key: 2, attrs: {oninit: oninit2}},
+			{tag: "p", key: 3, attrs: {oninit: oninit3}},
+		])
+		render(root, [
+			{tag: "p", key: 1, attrs: {oninit: oninit1}},
+			{tag: "p", key: 3, attrs: {oninit: oninit3}},
+		])
+		render(root, [
+			{tag: "p", key: 3, attrs: {oninit: oninit3}},
+		])
+
+		o(oninit1.callCount).equals(1)
+		o(oninit2.callCount).equals(1)
+		o(oninit3.callCount).equals(1)
+	})
 })