morphdom is a lightweight DOM diffing and patching library that transforms an existing DOM tree to match a target DOM tree without requiring a virtual DOM.
The problem morphdom solves is preserving internal DOM state during UI updates. When a component rerenders, simply replacing the entire DOM tree with innerHTML loses scroll positions, input caret positions, CSS transition states, and other browser-maintained state. morphdom instead performs a minimal set of changes to transform the existing DOM to match the target, keeping the real DOM as the source of truth. The algorithm works in a single pass over both trees and automatically matches elements by ID when they appear in both the original and target trees.
The tool suits projects where you need efficient DOM updates while preserving user interaction state, particularly when working with templating languages that produce HTML strings. Because morphdom operates on the real DOM rather than a virtual representation, it works with any templating approach and handles manual DOM manipulations correctly. It supports both real DOM nodes and virtual DOM nodes as input, with virtual nodes automatically upgraded to real DOM nodes when needed.
The project shows consistent maintenance with regular updates addressing edge cases and browser compatibility. Development includes active bug fixes and feature additions that expand the tool's capabilities, such as the introduction of virtual DOM support. The codebase maintains backward compatibility while evolving to handle new use cases, and documentation is kept current with examples and detailed API specifications.
