React Layout Primitives: react-dock vs react-resize-panel vs react-split-pane

Building flexible user interfaces often requires letting users control how much space different components occupy. Whether it's a code editor with a sidebar, a chat widget that slides in, or a dashboard with adjustable grids, the underlying mechanics involve handling mouse events, calculating dimensions, and updating the DOM efficiently. react-split-pane, react-dock, and react-resize-panel all address these needs but target distinct interaction patterns. Let's look at how they differ in practice.

🖥️ Core Interaction Model: Split Views vs Sliding Drawers vs Custom Panels

The most critical difference lies in how these libraries conceptualize the layout.

react-split-pane is built around the concept of two fixed panes separated by a draggable "splitter." It assumes a binary layout: Pane A and Pane B share the available space. When you drag the handle, one grows while the other shrinks. This is perfect for side-by-side comparisons or master-detail views.

// react-split-pane: Two panes sharing space
import SplitPane from 'react-split-pane';

function EditorLayout() {
  return (
    <SplitPane split="vertical" minSize={200} defaultSize={300}>
      <div className="sidebar">File Explorer</div>
      <div className="code-area">Code Editor</div>
    </SplitPane>
  );
}

react-dock treats the panel as an overlay that slides in from an edge. It doesn't push content away in the same permanent way; instead, it often overlaps or resizes a container to reveal itself. The primary state is "docked" (visible) vs "undocked" (hidden or minimized), rather than a continuous ratio between two equal peers.

// react-dock: Sliding drawer from the right
import Dock from 'react-dock';

function DebugConsole() {
  const [isOpen, setIsOpen] = React.useState(false);

  return (
    <>
      <button onClick={() => setIsOpen(!isOpen)}>Toggle Console</button>
      <Dock position="right" size={0.4} isOpen={isOpen}>
        <div className="console-output">Logs appear here...</div>
      </Dock>
    </>
  );
}

react-resize-panel provides a raw container that can be resized by dragging its edges or corners. It doesn't enforce a "two-pane" rule or a "docking" behavior. You define the handle, and the library manages the dimension updates. This gives you the freedom to build multi-pane grids or irregular layouts where the resizing logic is unique to your design.

// react-resize-panel: Custom resizable box
import { ResizePanel } from 'react-resize-panel';

function CustomWidget() {
  return (
    <ResizePanel 
      width={300} 
      height={200} 
      onResize={(size) => console.log(size)}
      handleClasses={{ right: 'custom-handle' }}
    >
      <div>Content that can be stretched freely</div>
    </ResizePanel>
  );
}

📐 Layout Direction and Constraints

How you control the direction of resizing and set limits varies significantly between the three.

react-split-pane uses a simple split prop to toggle between "horizontal" (top/bottom) and "vertical" (left/right). It has robust built-in props for minSize and maxSize to prevent panes from collapsing completely or growing too large, which is essential for usability.

// react-split-pane: Vertical split with constraints
<SplitPane 
  split="vertical" 
  minSize={100} 
  maxSize={500}
  defaultSize={250}
>
  <LeftPane />
  <RightPane />
</SplitPane>

react-dock uses a position prop accepting strings like "left", "right", "top", or "bottom". The size is often controlled as a fraction of the screen (0 to 1) or a fixed pixel value, and it relies on the isOpen state to trigger the animation. Constraints are less about preventing collapse and more about defining the maximum extent of the drawer.

// react-dock: Top dock with fractional size
<Dock 
  position="top" 
  size={0.3} 
  isOpen={true}
  dimMode="none"
>
  <NotificationBar />
</Dock>

react-resize-panel requires you to specify which edges are resizable. You might enable resizing only on the right edge, or both width and height. It doesn't inherently know about "min" or "max" sizes in the same declarative way; you often need to handle these limits inside the onResize callback and feed the clamped values back into the component.

// react-resize-panel: Resizable only on the right edge
<ResizePanel 
  width={400}
  resizeEdges={{ right: true, left: false, top: false, bottom: false }}
  onResize={(newSize) => {
    if (newSize.width < 100) return; // Manual constraint
    setWidth(newSize.width);
  }}
>
  <FlexibleContent />
</ResizePanel>

🎨 Styling and Customization

Visual integration is key for layout components since they sit at the structural level of your app.

react-split-pane renders a specific DOM structure with a dedicated "resizer" div between your children. It applies inline styles for positioning but allows you to pass custom class names via props like className and resizerClassName. This makes it easy to theme the splitter handle to match your design system.

// react-split-pane: Customizing the splitter handle
<SplitPane 
  split="horizontal"
  resizerClassName="my-custom-resizer"
  pane1ClassName="pane-top"
  pane2ClassName="pane-bottom"
>
  {/* content */}
</SplitPane>

/* CSS */
.my-custom-resizer {
  background: #333;
  height: 5px;
  transition: background 0.2s;
}
.my-custom-resizer:hover {
  background: #007bff;
}

react-dock focuses on transition effects. It supports different dimMode options to darken the background behind the dock when it opens. You can customize the dock's container style directly, but the library handles the transform animations (sliding in/out) internally. This reduces the CSS burden but limits how much you can tweak the animation physics without overriding internal styles.

// react-dock: Dimming the background
<Dock 
  position="left" 
  size={0.5} 
  isOpen={true}
  dimMode="dark" // Built-in backdrop dimming
  dockStyle={{ background: '#fff' }}
>
  <SidebarContent />
</Dock>

react-resize-panel is the most stylistically neutral. It renders a wrapper div and the handles you request. You are responsible for styling the handles completely, including their cursor states (e.g., cursor: ew-resize). This is powerful if you need handles that look like borders, floating buttons, or invisible touch zones, but it requires more CSS setup.

// react-resize-panel: Fully custom handle styling
<ResizePanel 
  width={300}
  handleClasses={{ right: 'my-thick-handle' }}
>
  <Content />
</ResizePanel>

/* CSS */
.my-thick-handle {
  width: 10px;
  background: rgba(0,0,0,0.1);
  position: absolute;
  right: 0;
  top: 0;
  bottom: 0;
}
.my-thick-handle:hover {
  background: rgba(0,0,0,0.3);
}

⚠️ Maintenance and Deprecation Status

A crucial factor in architectural decisions is the long-term viability of the library.

react-split-pane is widely adopted and generally considered stable. While development pace may vary, it remains the de facto standard for split layouts in the React ecosystem. Many forks and maintained versions exist if the original repository slows down, ensuring you aren't locked into a dead end.

react-dock has seen periods of low activity. While it still functions for basic use cases, it may lack support for newer React patterns (like strict mode quirks or modern hook-based internal state). If you choose this, be prepared to potentially fork it or wrap it to handle edge cases in modern React versions.

react-resize-panel is a smaller, more niche utility. It is less likely to have a massive community backing it. Because it is a lower-level primitive, it is less prone to breaking due to high-level React changes, but you should verify its compatibility with your specific React version before committing. If the project appears unmaintained, implementing a custom hook with native pointer events might be a safer long-term bet.

🌐 Real-World Scenarios

Scenario 1: IDE or Code Editor

You are building a web-based code editor. Users need a file tree on the left and code on the right, with the ability to adjust the width of the file tree.

• ✅ Best choice: react-split-pane
• Why? It handles the vertical split, the drag handle, and the min/max constraints out of the box. The mental model matches the UI perfectly.

<SplitPane split="vertical" defaultSize={200}>
  <FileTree />
  <CodeEditor />
</SplitPane>

Scenario 2: Customer Support Chat Widget

You need a chat window that sits hidden on the right edge of the screen and slides out when the user clicks a button, overlapping the main content slightly.

• ✅ Best choice: react-dock
• Why? The "slide-in" animation and edge positioning are its core features. Implementing this with split-pane would require complex CSS hacks to simulate the overlay behavior.

<Dock position="right" size={350} isOpen={isChatOpen}>
  <ChatWindow />
</Dock>

Scenario 3: Drag-and-Drop Dashboard Builder

Users can place widgets anywhere on a canvas and resize them by dragging any corner or edge to create a masonry-style layout.

• ✅ Best choice: react-resize-panel
• Why? You need granular control over which edges are resizable and how the resize events propagate. Neither split-pane (binary) nor dock (edge-only) can handle free-form corner resizing.

<ResizePanel 
  width={w} 
  height={h} 
  resizeEdges={{ right: true, bottom: true, left: true, top: true }}
  onResize={handleWidgetResize}
>
  <WidgetContent />
</ResizePanel>

📊 Summary: Key Differences

💡 The Big Picture

Choosing the right tool depends entirely on the user experience you want to deliver.

react-split-pane is the workhorse for structural layouts. If your UI is defined by distinct sections that share screen real estate permanently, this is the safest and most robust choice. It solves the "drag to resize" problem so well that it has become a standard pattern.

react-dock is specialized for auxiliary interfaces. If your panel is something the user toggles on and off, and it should feel like it's emerging from the edge of the screen, this library saves you from writing complex CSS transitions and position math.

react-resize-panel is the builder's choice. When the standard patterns don't fit—perhaps you need a resizable card in a grid, or a panel that resizes from the center out—this gives you the raw materials to construct it without fighting against opinionated defaults.

Final Thought: Always verify the maintenance status of these libraries before installation. For critical production apps, if a library feels stale, consider that the logic for resizing (handling mouse/touch events and updating state) is often simple enough to implement as a custom hook, giving you full ownership and zero dependencies.