refactor(examples): switch examples from cra to nextjs

examples/nextjs/pages/CustomConnectionLine/ConnectionLine.tsx

@@ -0,0 +1,31 @@
+import React, { FC } from 'react';
+import { ConnectionLineComponentProps } from '@react-flow/core';
+
+const ConnectionLine: FC<ConnectionLineComponentProps> = ({
+  sourceX,
+  sourceY,
+  targetX,
+  targetY,
+}) => {
+  return (
+    <g>
+      <path
+        fill='none'
+        stroke='#222'
+        strokeWidth={1.5}
+        className='animated'
+        d={`M${sourceX},${sourceY} C ${sourceX} ${targetY} ${sourceX} ${targetY} ${targetX},${targetY}`}
+      />
+      <circle
+        cx={targetX}
+        cy={targetY}
+        fill='#fff'
+        r={3}
+        stroke='#222'
+        strokeWidth={1.5}
+      />
+    </g>
+  );
+};
+
+export default ConnectionLine;

examples/nextjs/pages/CustomConnectionLine/index.tsx

@@ -0,0 +1,47 @@
+import React, { useCallback } from 'react';
+import ReactFlow, {
+  Node,
+  addEdge,
+  Background,
+  BackgroundVariant,
+  Connection,
+  Edge,
+  useNodesState,
+  useEdgesState,
+} from '@react-flow/core';
+
+import ConnectionLine from './ConnectionLine';
+
+const initialNodes: Node[] = [
+  {
+    id: '1',
+    type: 'default',
+    data: { label: 'Node 1' },
+    position: { x: 250, y: 5 },
+  },
+];
+const initialEdges: Edge[] = [];
+
+const ConnectionLineFlow = () => {
+  const [nodes, , onNodesChange] = useNodesState(initialNodes);
+  const [edges, setEdges, onEdgesChange] = useEdgesState(initialEdges);
+  const onConnect = useCallback(
+    (params: Connection | Edge) => setEdges((eds) => addEdge(params, eds)),
+    [setEdges]
+  );
+
+  return (
+    <ReactFlow
+      nodes={nodes}
+      edges={edges}
+      onNodesChange={onNodesChange}
+      onEdgesChange={onEdgesChange}
+      connectionLineComponent={ConnectionLine}
+      onConnect={onConnect}
+    >
+      <Background variant={BackgroundVariant.Lines} />
+    </ReactFlow>
+  );
+};
+
+export default ConnectionLineFlow;