feat(website): init

website/src/markdown/docs/api/helper-functions.md

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+---
+title: Helper Functions
+---
+
+If you want to remove a node or connect two nodes with each other you need to pass a function to `onElementsRemove` and `onConnect`. In order to simplify this process there are some helper functions you can use:
+
+```javascript
+import ReactFlow, { isNode, isEdge, removeElements, addEdge } from 'react-flow-renderer';
+```
+
+### `isEdge`
+
+Returns `true` if the passed element is an edge.
+
+`isEdge = (element: Node | Edge): element is Edge`
+
+### `isNode`
+
+Returns `true` if the passed element is a node.
+
+`isNode = (element: Node | Edge): element is Node`
+
+### `removeElements`
+
+Returns an array of elements without the ones from `elementsToRemove`. It also removes all incoming/outgoing edges if you just pass one or multiple nodes.
+
+`removeElements = (elementsToRemove: Elements, elements: Elements): Elements`
+
+### `addEdge`
+
+Returns an array with elements with the added edge.
+
+`addEdge = (edgeParams: Edge, elements: Elements): Elements`
+
+### `getOutgoers`
+
+Returns all direct child nodes of the passed node.
+
+`getOutgoers = (node: Node, elements: Elements): Node[]`
+
+### `getIncomers`
+
+Returns all direct incoming nodes of the passed node.
+
+`getIncomers = (node: Node, elements: Elements): Node[]`
+
+### `getConnectedEdges`
+
+Returns all edges that are connected to the passed nodes.
+
+`getConnectedEdges = (nodes: Node[], edges: Edge[]): Edge[]`
+
+You can use these function as seen in [this example](/example/src/Overview/index.js#L40-L41) or use your own ones.