feat: add Node.getIf method (#5723)

* feat: add Node.getIf support

* chore: restructure get to use getIf

.changeset/clean-icons-bow.md

@@ -0,0 +1,5 @@
+---
+'slate': patch
+---
+
+feat: add Node.getIf method

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.
    */
@@ -389,17 +394,25 @@ export const Node: NodeInterface = {
   },
 
   get(root: Node, path: Path): Node {
+    const node = Node.getIf(root, path)
+    if (node === undefined) {
+      throw new Error(
+        `Cannot find a descendant at path [${path}] in node: ${Scrubber.stringify(
+          root
+        )}`
+      )
+    }
+    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]) {
-        throw new Error(
-          `Cannot find a descendant at path [${path}] in node: ${Scrubber.stringify(
-            root
-          )}`
-        )
+        return
       }
 
       node = node.children[p]

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