react-resizable-panels

React components for resizable panel groups/layouts

import { Panel, PanelGroup, PanelResizeHandle } from "react-resizable-panels";

<PanelGroup autoSaveId="example" direction="horizontal">
  <Panel defaultSize={25}>
    <SourcesExplorer />
  </Panel>
  <PanelResizeHandle />
  <Panel>
    <SourceViewer />
  </Panel>
  <PanelResizeHandle />
  <Panel defaultSize={25}>
    <Console />
  </Panel>
</PanelGroup>;

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Props

PanelGroup

prop	type	description
autoSaveId	?string	Unique id used to auto-save group arrangement via localStorage
children	ReactNode	Arbitrary React element(s)
className	?string	Class name to attach to root element
direction	"horizontal" | "vertical"	Group orientation
id	?string	Group id; falls back to useId when not provided
onLayout	?(sizes: number[]) => void	Called when group layout changes
storage	?PanelGroupStorage	Custom storage API; defaults to localStorage 1
style	?CSSProperties	CSS style to attach to root element
tagName	?string = "div"	HTML element tag name for root element

¹: Storage API must define the following synchronous methods:

• getItem: (name:string) => string
• setItem: (name: string, value: string) => void

PanelGroup components also expose an imperative API for manual resizing:

method	description
getId(): string	Gets the panel group's ID.
getLayout(): number[]	Gets the panel group's current layout ([1 - 100, ...]).
setLayout(layout: number[])	Resize panel group to the specified layout ([1 - 100, ...]).

Panel

prop	type	description
children	ReactNode	Arbitrary React element(s)
className	?string	Class name to attach to root element
collapsedSize	?number=0	Panel should collapse to this size
collapsible	?boolean=false	Panel should collapse when resized beyond its minSize
defaultSize	?number	Initial size of panel (numeric value between 1-100)
id	?string	Panel id (unique within group); falls back to useId when not provided
maxSize	?number = 100	Maximum allowable size of panel (numeric value between 1-100); defaults to 100
minSize	?number = 10	Minimum allowable size of panel (numeric value between 1-100); defaults to 10
onCollapse	?() => void	Called when panel is collapsed
onExpand	?() => void	Called when panel is expanded
onResize	?(size: number) => void	Called when panel is resized; size parameter is a numeric value between 1-100. 1
order	?number	Order of panel within group; required for groups with conditionally rendered panels
style	?CSSProperties	CSS style to attach to root element
tagName	?string = "div"	HTML element tag name for root element

¹: If any Panel has an onResize callback, the order prop should be provided for all Panels.

Panel components also expose an imperative API for manual resizing:

method	description
collapse()	If panel is collapsible, collapse it fully.
expand()	If panel is currently collapsed, expand it to its most recent size.
getId(): string	Gets the ID of the panel.
getSize(): number	Gets the current size of the panel as a percentage (1 - 100).
isCollapsed(): boolean	Returns true if the panel is currently collapsed (size === 0).
isExpanded(): boolean	Returns true if the panel is currently not collapsed (!isCollapsed()).
getSize(): number	Returns the most recently committed size of the panel as a percentage (1 - 100).
resize(size: number)	Resize panel to the specified percentage (1 - 100).

PanelResizeHandle

prop	type	description
children	?ReactNode	Custom drag UI; can be any arbitrary React element(s)
className	?string	Class name to attach to root element
hitAreaMargins	?{ coarse: number = 15; fine: number = 5; }	Allow this much margin when determining resizable handle hit detection
disabled	?boolean	Disable drag handle
id	?string	Resize handle id (unique within group); falls back to useId when not provided
onDragging	?(isDragging: boolean) => void	Called when group layout changes
style	?CSSProperties	CSS style to attach to root element
tagName	?string = "div"	HTML element tag name for root element

---

FAQ

Can panel sizes be specified in pixels?

No. Pixel-based constraints added significant complexity to the initialization and validation logic and so I've decided not to support them. You may be able to implement a version of this yourself following a pattern like this but it is not officially supported by this library.

How can I fix layout/sizing problems with conditionally rendered panels?

The Panel API doesn't require id and order props because they aren't necessary for static layouts. When panels are conditionally rendered though, it's best to supply these values.

<PanelGroup direction="horizontal">
  {renderSideBar && (
    <>
      <Panel id="sidebar" minSize={25} order={1}>
        <Sidebar />
      </Panel>
      <PanelResizeHandle />
    </>
  )}
  <Panel minSize={25} order={2}>
    <Main />
  </Panel>
</PanelGroup>

Can a attach a ref to the DOM elements?

No. I think exposing two refs (one for the component's imperative API and one for a DOM element) would be awkward. This library does export several utility methods for accessing the underlying DOM elements though. For example:

import {
  getPanelElement,
  getPanelGroupElement,
  getResizeHandleElement,
  Panel,
  PanelGroup,
  PanelResizeHandle,
} from "react-resizable-panels";

export function Example() {
  const refs = useRef();

  useEffect(() => {
    const groupElement = getPanelGroupElement("group");
    const leftPanelElement = getPanelElement("left-panel");
    const rightPanelElement = getPanelElement("right-panel");
    const resizeHandleElement = getResizeHandleElement("resize-handle");

    // If you want to, you can store them in a ref to pass around
    refs.current = {
      groupElement,
      leftPanelElement,
      rightPanelElement,
      resizeHandleElement,
    };
  }, []);

  return (
    <PanelGroup direction="horizontal" id="group">
      <Panel id="left-panel">{/* ... */}</Panel>
      <PanelResizeHandle id="resize-handle" />
      <Panel id="right-panel">{/* ... */}</Panel>
    </PanelGroup>
  );
}

Why don't I see any resize UI?

This likely means that you haven't applied any CSS to style the resize handles. By default, a resize handle is just an empty DOM element. To add styling, use the className or style props:

// Tailwind example
<PanelResizeHandle className="w-2 bg-blue-800" />

How can I use persistent layouts with SSR?

By default, this library uses localStorage to persist layouts. With server rendering, this can cause a flicker when the default layout (rendered on the server) is replaced with the persisted layout (in localStorage). The way to avoid this flicker is to also persist the layout with a cookie like so:

Server component

import ResizablePanels from "@/app/ResizablePanels";
import { cookies } from "next/headers";

export function ServerComponent() {
  const layout = cookies().get("react-resizable-panels:layout");

  let defaultLayout;
  if (layout) {
    defaultLayout = JSON.parse(layout.value);
  }

  return <ClientComponent defaultLayout={defaultLayout} />;
}

Client component

"use client";

import { Panel, PanelGroup, PanelResizeHandle } from "react-resizable-panels";

export function ClientComponent({
  defaultLayout = [33, 67],
}: {
  defaultLayout: number[] | undefined;
}) {
  const onLayout = (sizes: number[]) => {
    document.cookie = `react-resizable-panels:layout=${JSON.stringify(sizes)}`;
  };

  return (
    <PanelGroup direction="horizontal" onLayout={onLayout}>
      <Panel defaultSize={defaultLayout[0]}>{/* ... */}</Panel>
      <PanelResizeHandle className="w-2 bg-blue-800" />
      <Panel defaultSize={defaultLayout[1]}>{/* ... */}</Panel>
    </PanelGroup>
  );
}

A demo of this is available here.