HTML restrictions

Explain some of the restrictions we impose to balance minimal implementation and being able to implement all targeted user applications.

• Mandatory
•   script
• Quality of life improvement
•   noscript
•   javascript: URI
• To research
•   audio playback
•   inline links
•   table
•   images
•   iframe
• Partial
• Unsupported

script

• Verdict: partial, also allow src attribute
• Implementation complexity: high, but manageable in terms of cost to benefit
• Restriction: only JavaScript0 is allowed
• Incidence rate: high
• Use case: backend-optional computation, privacy, improving latency, reducing server hosting cost, logic can be changed by visitor
• Workaround: server side rendering
• Standard: NS2 for `script`, NS3 for `src` attribute

See:

• js-spec.md
• js-choices.md
• js-grammar.md

Quality of life improvement

noscript

• Verdict: discouraged
• Reason: use progressive enhancement instead
• Implementation complexity: trivial
• Use case: fallback when JavaScript is not implemented or disabled
• Workaround: greet with a "noscript" message and only hide it after the full JavaScript code has loaded successfully
• Standard: NS2

javascript: URI

• Verdict: recommended
• Reason: the simplest alternative for client side interaction
• Incidence rate: very high
• Use case: client side interactions, form processing, validation, bookmarklets
• Implementation complexity: trivial
• Workaround: implement event handlers such as onclick and onsubmit or navigate to a URI pointing to (or submit a form targeting) an HTML containing JavaScript that dispatches upon loading, encode the link identifier and serialize the whole application state to the URI query or anchor
• Standard: NS2

To research

audio playback

• Verdict: partial
• Implementation complexity: high, platform dependent sound libraries
• Restriction: only uncompressed PCM wav codec
• Incidence rate: low
• Use case: web radio, lecture, push-to-talk conference call
• Workaround: download or pass to protocol handler, although it can't solve programmatic use cases

inline links

• Verdict: probably supported
• Implementation complexity: low with footnotes on their own lines, intermediate when inline
• Drawback: does not map to gemini
• Incidence rate: very high
• Use case: buttons on planar game board within a (preformatted) table
• Workaround: put links on their own line

table

• Verdict: probably unsupported
• Implementation complexity: high, layout
• Incidence rate: intermediate
• Use case: tabular data chart, game board
• Workaround: list, preformatted text

images

• Verdict: probably unsupported
• Implementation complexity: very high, codecs, layout, rendering
• Drawback: more round trips if external
• Incidence rate: high
• Use case: photos, diagrams
• Workaround: download or pass to protocol handler

iframe

• Verdict: probably unsupported
• Implementation complexity: high, isolate more state, nesting depth, frame busting
• Drawbacks: more round trips if external
• Incidence rate: low
• Use cases: third party integration, the only standard way for native JavaScript eval sandboxing within a code snippet pad
• Workaround: XMLHttpRequest

Partial

Unsupported

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