ink-scroll-list

ink-scroll-list

A high-level ScrollList component for Ink CLI applications, built on top of ink-scroll-view.

📖 Documentation Website

✨ Features

• Controlled Selection: Selection state is managed by the parent via selectedIndex prop.
• Auto-Scrolling: Automatically scrolls to ensure the selected item is visible.
• Flexible Alignment: Control how the selected item aligns in the viewport (auto, top, bottom, center).
• Performance: Optimized to track selection position efficiently without full re-layouts.
• Responsive: Maintains selection visibility when viewport or content changes.

🎬 Demos

Selection & Navigation

Scroll Alignment Modes

Expand/Collapse

Dynamic Items

📦 Installation

npm install ink-scroll-list
# Peer dependencies
npm install ink react

🚀 Usage

ScrollList is a controlled component - the parent component owns and manages the selection state via the selectedIndex prop.

import React, { useRef, useState } from "react";
import { render, Text, Box, useInput } from "ink";
import { ScrollList, ScrollListRef } from "ink-scroll-list";

const App = () => {
  const listRef = useRef<ScrollListRef>(null);
  const [selectedIndex, setSelectedIndex] = useState(0);
  const items = Array.from({ length: 20 }).map((_, i) => `Item ${i + 1}`);

  // Handle keyboard navigation in the parent
  useInput((input, key) => {
    if (key.upArrow) {
      setSelectedIndex((prev) => Math.max(prev - 1, 0));
    }
    if (key.downArrow) {
      setSelectedIndex((prev) => Math.min(prev + 1, items.length - 1));
    }
    if (input === "g") {
      setSelectedIndex(0); // Jump to first
    }
    if (input === "G") {
      setSelectedIndex(items.length - 1); // Jump to last
    }
    if (key.return) {
      console.log(`Selected: ${items[selectedIndex]}`);
    }
  });

  return (
    <Box borderStyle="single" height={10}>
      <ScrollList ref={listRef} selectedIndex={selectedIndex}>
        {items.map((item, i) => (
          <Box key={i}>
            <Text color={i === selectedIndex ? "green" : "white"}>
              {i === selectedIndex ? "> " : "  "}
              {item}
            </Text>
          </Box>
        ))}
      </ScrollList>
    </Box>
  );
};

render(<App />);

📚 API Reference

For detailed API documentation, see API Reference.

Props (ScrollListProps)

Extends ScrollViewProps from ink-scroll-view.

Prop	Type	Description
selectedIndex	number	The currently selected item index (controlled).
scrollAlignment	'auto' | 'top' | 'bottom' | 'center'	Alignment mode for selected item. Default: 'auto'.
...	ScrollViewProps	All props from ScrollView.

Scroll Alignment Modes

• 'auto' (default): Minimal scrolling to bring the item into view. Best for keyboard navigation.
• 'top': Always aligns the selected item to the top of the viewport.
• 'bottom': Always aligns the selected item to the bottom of the viewport.
• 'center': Always centers the selected item in the viewport. Best for search/spotlight UX.

Ref Methods (ScrollListRef)

Extends ScrollViewRef from ink-scroll-view. Access these via ref.current.

Note: When a selectedIndex is set, all scroll methods are constrained to keep the selected item visible. This prevents accidentally scrolling the selection out of view.

Method	Signature	Description
scrollTo	(y: number) => void	Scroll to a specific offset (constrained to keep selection visible).
scrollBy	(delta: number) => void	Scroll by a relative amount (constrained).
scrollToTop	() => void	Scroll as far up as possible while keeping selection visible.
scrollToBottom	() => void	Scroll as far down as possible while keeping selection visible.
getScrollOffset	() => number	Get current scroll offset.
getContentHeight	() => number	Get total content height.
getViewportHeight	() => number	Get viewport height.
getBottomOffset	() => number	Get distance from bottom.
getItemHeight	(index: number) => number	Get a specific item's height.
getItemPosition	(index: number) => {top, height} | null	Get a specific item's position.
remeasure	() => void	Force remeasurement of all items.
remeasureItem	(index: number) => void	Force remeasurement of a specific item.

Large Items: For items that are larger than the viewport, scrolling is allowed within the item's bounds. This lets users scroll to see different parts of the large item while at least part of it remains visible.

💡 Tips

• Controlled Component Pattern: ScrollList is a fully controlled component. The parent must manage selectedIndex and update it based on user input.

• Input Handling: Use useInput from Ink to handle keyboard events and update selectedIndex accordingly. The component does NOT handle input internally.

• Terminal Resizing: Ink components don't automatically know when the terminal window resizes. Listen to process.stdout's resize event and call remeasure() on the ref:

  useEffect(() => {
    const handleResize = () => listRef.current?.remeasure();
    process.stdout.on("resize", handleResize);
    return () => process.stdout.off("resize", handleResize);
  }, []);
  

• Dynamic Items: When items are added or removed, the parent should update selectedIndex if necessary:

  • When adding items at the beginning: setSelectedIndex(prev => prev + addedCount)
  • When removing items: Clamp to valid range: setSelectedIndex(prev => Math.min(prev, newLength - 1))

• Performance: ScrollList uses ink-scroll-view under the hood, so it benefits from the same performance optimizations (item height caching, efficient re-layouts).

⚠️ Breaking Changes in v0.4.0

This version introduces a major architectural change: ScrollList is now a fully controlled component.

Removed Features

The following props have been removed:

• onSelectionChange - No longer needed; parent owns the state directly.

The following ref methods have been removed:

• select(index, mode) - Use setSelectedIndex(index) + scrollAlignment prop instead.
• selectNext() - Use setSelectedIndex(prev => Math.min(prev + 1, length - 1)) instead.
• selectPrevious() - Use setSelectedIndex(prev => Math.max(prev - 1, 0)) instead.
• selectFirst() - Use setSelectedIndex(0) instead.
• selectLast() - Use setSelectedIndex(length - 1) instead.
• scrollToItem(index, mode) - Use selectedIndex prop instead.
• getSelectedIndex() - Parent already knows the index.
• getItemCount() - Parent already knows the item count.

Migration Guide

Before (v0.3.x):

const listRef = useRef<ScrollListRef>(null);
const [selectedIndex, setSelectedIndex] = useState(0);

useInput((input, key) => {
  if (key.downArrow) {
    const newIndex = listRef.current?.selectNext() ?? 0;
    setSelectedIndex(newIndex);
  }
});

<ScrollList ref={listRef} selectedIndex={selectedIndex} onSelectionChange={setSelectedIndex}>
  {items.map(...)}
</ScrollList>

After (v0.4.0):

const listRef = useRef<ScrollListRef>(null);
const [selectedIndex, setSelectedIndex] = useState(0);

useInput((input, key) => {
  if (key.downArrow) {
    setSelectedIndex((prev) => Math.min(prev + 1, items.length - 1));
  }
});

<ScrollList ref={listRef} selectedIndex={selectedIndex}>
  {items.map(...)}
</ScrollList>

Why This Change?

The controlled component pattern provides:

• Predictability: The parent always knows the exact selection state.
• Simplicity: No need to sync internal state with external state.
• Flexibility: The parent has full control over how selection changes.
• Testability: Selection logic lives in the parent and is easy to unit test.

🔗 Related Packages

This package is part of a family of Ink scroll components:

Package	Description
ink-scroll-view	Core scroll container component
ink-scroll-list	A scrollable list with focus management and item selection (this package)
ink-scroll-bar	A standalone scrollbar component for any scroll container

License

MIT