Principles

gsx's design follows a few firm commitments. They explain most of the syntax decisions you'll meet in the syntax guide.

Stay close to HTML and to Go

Markup looks like HTML/JSX; helpers, variant functions, and everything that isn't a template are ordinary Go. There is no third language between them — the seam is the component keyword and { } interpolation.

Syntax tidiness is the top priority

Parser complexity bends to serve clean syntax, never the reverse. Where it buys tidier markup, gsx does targeted Go-expression boundary parsing rather than forcing an awkward syntax to keep the parser simple.

Lean on the Go compiler

Generated code is plain Go. Prop names, types, and call sites are checked by the Go compiler, not by gsx at runtime. A wrong template is a compile error with a real source location (gsx emits //line directives back to the .gsx), not a runtime surprise.

Embrace the build step

gsx compiles .gsx → .x.go → go build rather than interpreting templates at runtime — that compile step is what makes the type-safety above possible. We treat it as a feature, not a tax: the @gsxhq/vite-plugin-gsx plugin regenerates and live-reloads on save (gsx init wires it up), so the loop stays instant. A build step you never wait on is just a faster, safer template.

Secure by construction

Interpolation is auto-escaped by default, and escaping is context-aware: text, attribute, URL, and CSS contexts each get the right treatment — determined at codegen from the value's position, not by the author wrapping values manually. URLs are checked against a scheme allow-list, <style>/style= values pass a CSS value-filter, attribute values are always quoted, and JS contexts with no safe encoding yet (bare expressions in on*/event handlers) are compile errors, not runtime surprises.

The opt-outs are explicit and auditable — each a deliberate, grep-able bypass of one specific check: gsx.Raw(s) for trusted HTML, gsx.RawURL(s) for a URL whose scheme you vouch for, and gsx.RawCSS(s) for trusted CSS. Type-driven attributes mean a bool renders as a bare or omitted attribute rather than the string "true".

Standard-library-only runtime

The gsx runtime package imports nothing outside the Go standard library. The generator/CLI may use golang.org/x/tools, but what ships in your binary stays stdlib-only.