Remove snabbdom dependency with minimal pure DOM implementation

[Copilot]

Replaces snabbdom with a lightweight (~245 LOC) pure JavaScript DOM manipulation layer. Zero runtime dependencies.

Changes

src/render.mjs - Complete rewrite

• Custom createElement() for DOM creation from virtual nodes
• Diffing/patching via updateElement(), updateAttributes(), updateProperties(), updateStyles()
• Preserves existing API: render(tree, node, oldTree) signature unchanged

package.json

• Removed snabbdom: 3.5.1 dependency
• Bundle size: 6KB → 4.3KB (28% smaller)

README.md

• Updated to reflect zero dependencies

Implementation

The new implementation handles all snabbdom features used by pureact:

// Creates real DOM from virtual nodes
function createElement(vnode) {
  if (typeof vnode === 'string' || typeof vnode === 'number') {
    return document.createTextNode(String(vnode))
  }
  
  const el = document.createElement(vnode.tagName)
  
  // Handles attrs, props (including event listeners), styles
  // Recursively creates children
  // ...
}

// Efficient diffing and patching
function updateElement(parent, newNode, oldNode, index) {
  // Handles additions, removals, replacements, updates
  // Updates attrs/props/styles only when changed
  // Recursively diffs children
  // ...
}

Supports:

• Event listeners (onclick, etc.)
• Properties (className, value, checked)
• Attributes and styles
• Text and element nodes
• Nested children

Demo

Interactive counter showing component rendering, store integration, and event handling working correctly.

[!WARNING]

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• googlechromelabs.github.io
  • Triggering command: node install.mjs (dns block)
• https://storage.googleapis.com/chrome-for-testing-public/142.0.7444.162/linux64/chrome-linux64.zip
  • Triggering command: node install.mjs (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

Try to remove the dependency to snabbdom by implementing the basic dom manipulating techniques in the same style as the rest of the codebase, minimal and pure

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