update checked property based on current element value. fixes #950

src/modules/props.ts

@@ -7,6 +7,7 @@ function updateProps(oldVnode: VNode, vnode: VNode): void {
   let key: string;
   let cur: any;
   let old: any;
+  let shouldUpdate: boolean;
   const elm = vnode.elm;
   let oldProps = (oldVnode.data as VNodeData).props;
   let props = (vnode.data as VNodeData).props;
@@ -19,10 +20,26 @@ function updateProps(oldVnode: VNode, vnode: VNode): void {
   for (key in props) {
     cur = props[key];
     old = oldProps[key];
-    if (old !== cur && (key !== "value" || (elm as any)[key] !== cur)) {
+
+    // DOM INPUT.value should never be updated when it matches the new vnode.
+    // typing into an INPUT with a sync event handler cause a render (such as for
+    // validation feedback) where setting INPUT.value also pushes the cursor to the end
+    // of the input. fixes #71, partially fixes #63
+    if (key === 'value')
+      shouldUpdate = (old !== cur) && ((elm as any)[key] !== cur);
+
+    // DOM INPUT.checked is a boolean property. The element's internal value should be
+    // used for comparison. fixes #950
+    else if (key === 'checked')
+      shouldUpdate = (elm as any)[key] !== cur;
+
+    else
+      shouldUpdate = (old !== cur);
+
+
+    if (shouldUpdate)
       (elm as any)[key] = cur;
   }
-  }
 }
 
 export const propsModule: Module = { create: updateProps, update: updateProps };