fix: v-for update on move (#79)

Author: nooooooom

src/directives/for.ts

@@ -124,38 +124,43 @@ export const _for = (el: Element, exp: string, ctx: Context) => {
       blocks = childCtxs.map((s) => mountBlock(s, anchor))
       mounted = true
     } else {
-      const nextBlocks: Block[] = []
       for (let i = 0; i < blocks.length; i++) {
         if (!keyToIndexMap.has(blocks[i].key)) {
           blocks[i].remove()
         }
       }
-
+      
+      const nextBlocks: Block[] = []
       let i = childCtxs.length
+      let nextBlock: Block | undefined
+      let prevMovedBlock: Block | undefined
       while (i--) {
         const childCtx = childCtxs[i]
         const oldIndex = prevKeyToIndexMap.get(childCtx.key)
-        const next = childCtxs[i + 1]
-        const nextBlockOldIndex = next && prevKeyToIndexMap.get(next.key)
-        const nextBlock =
-          nextBlockOldIndex == null ? undefined : blocks[nextBlockOldIndex]
+        let block
         if (oldIndex == null) {
           // new
-          nextBlocks[i] = mountBlock(
+          block = mountBlock(
             childCtx,
             nextBlock ? nextBlock.el : anchor
           )
         } else {
           // update
-          const block = (nextBlocks[i] = blocks[oldIndex])
+          block = blocks[oldIndex]
           Object.assign(block.ctx.scope, childCtx.scope)
           if (oldIndex !== i) {
             // moved
-            if (blocks[oldIndex + 1] !== nextBlock) {
+            if (
+              blocks[oldIndex + 1] !== nextBlock || 
+              // If the next has moved, it must move too
+              prevMovedBlock === nextBlock
+            ) {
+              prevMovedBlock = block
               block.insert(parent, nextBlock ? nextBlock.el : anchor)
             }
           }
         }
+        nextBlocks.unshift(nextBlock = block)
       }
       blocks = nextBlocks
     }