It's a WIP.

Terms

• Highlight: A visual representation of a selection of text.

• Boundary: The edge of a highlight. There are two in each highlight.

• Active boundary: The boundary that is currently selected.

• Knob: The visual representation of a boundary.

• Caret: An insertion point within text.

• Selection (Web API)

• Range (Web API)

Ideas

• Use Node.compareDocumentPosition to avoid unintentional collapsed state
• Use partialContainment
• TextMetrics polyfill?
  • Nope
    • https://github.com/FormidableLabs/measure-text
    • https://www.npmjs.com/package/text-metrics
  • Maybe
    • https://github.com/motiz88/canvas-text-metrics-polyfill (!)
    • https://opentype.js.org/
    • https://github.com/Pomax/fontmetrics.js
    • https://github.com/soulwire/FontMetrics
• Is https://opentype.js.org/font-inspector.html useful?