feat: add Node.getIf support

packages/slate/src/interfaces/node.ts

@@ -131,6 +131,11 @@ export interface NodeInterface {
    */
   get: (root: Node, path: Path) => Node
 
+  /**
+   * Similar to get, but returns undefined if the node does not exist.
+   */
+  getIf: (root: Node, path: Path) => Node | undefined
+
   /**
    * Check if a descendant node exists at a specific path.
    */
@@ -408,6 +413,22 @@ export const Node: NodeInterface = {
     return node
   },
 
+  getIf(root: Node, path: Path): Node | undefined {
+    let node = root
+
+    for (let i = 0; i < path.length; i++) {
+      const p = path[i]
+
+      if (Text.isText(node) || !node.children[p]) {
+        return
+      }
+
+      node = node.children[p]
+    }
+
+    return node
+  },
+
   has(root: Node, path: Path): boolean {
     let node = root
 

packages/slate/test/interfaces/Node/getIf/root.tsx

@@ -0,0 +1,17 @@
+/** @jsx jsx  */
+import { Node } from 'slate'
+import { jsx } from 'slate-hyperscript'
+import { cloneDeep } from 'lodash'
+
+export const input = (
+  <editor>
+    <element>
+      <text />
+    </element>
+  </editor>
+)
+export const test = value => {
+  return Node.getIf(value, [])
+}
+export const skip = true // TODO: see https://github.com/ianstormtaylor/slate/pull/4188
+export const output = cloneDeep(input)

packages/slate/test/interfaces/Node/getIf/success.tsx

@@ -0,0 +1,19 @@
+/** @jsx jsx  */
+import { Node } from 'slate'
+import { jsx } from 'slate-hyperscript'
+
+export const input = (
+  <editor>
+    <element>
+      <text />
+    </element>
+  </editor>
+)
+export const test = value => {
+  return Node.getIf(value, [0])
+}
+export const output = (
+  <element>
+    <text />
+  </element>
+)

packages/slate/test/interfaces/Node/getIf/undefined.tsx

@@ -0,0 +1,15 @@
+/** @jsx jsx  */
+import { Node } from 'slate'
+import { jsx } from 'slate-hyperscript'
+
+export const input = (
+  <editor>
+    <element>
+      <text />
+    </element>
+  </editor>
+)
+export const test = value => {
+  return Node.getIf(value, [0, 0, 0])
+}
+export const output = undefined