From 427c593e42ad0c5d23e9200ce17fd61fbdddfae0 Mon Sep 17 00:00:00 2001
From: cat0825 <1759138827@qq.com>
Date: Sun, 31 May 2026 13:36:23 +0800
Subject: [PATCH] docs: clarify explicit grid tick values

---
 docs/marks/grid.md | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/docs/marks/grid.md b/docs/marks/grid.md
index d9d20180da..7c04e8c597 100644
--- a/docs/marks/grid.md
+++ b/docs/marks/grid.md
@@ -61,7 +61,24 @@ See the [axis mark](./axis.md) for more details and examples.
 
 ## Grid options
 
-The optional *data* is an array of tick values — it defaults to the scale’s ticks. The grid mark draws a line for each tick value, across the whole frame.
+The optional *data* is an array of tick values; if omitted, the mark computes its own ticks from the corresponding scale. To use the scale’s **ticks** option, use an implicit grid by setting the scale’s **grid** option, or pass the tick values directly to an explicit grid mark.
+
+For example, to align a grid with explicit tick values, pass the values to both the axis and grid marks:
+
+:::plot
+```js
+Plot.plot({
+  x: {
+    domain: [new Date(2026, 2, 9), new Date(2026, 2, 11)]
+  },
+  marks: [
+    ((ticks) => [Plot.gridX(ticks), Plot.axisX(ticks)])(
+      ["2026-03-09", "2026-03-10", "2026-03-11"].map((d) => new Date(d))
+    )
+  ]
+})
+```
+:::
 
 The following options are supported: