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Starlight Customizer

Scripting API

The customizer’s core is deliberately small. Four modules — state.js, emit-css.js, emit-apply.js, and ia.js — cover everything the panel does, and none of them touch the DOM.

State helpers

Section titled “State helpers”

defaultState() returns the starting ThemeState. getValue(state, id) reads a control’s current value or falls back to its manifest default. setValue(state, id, value) returns a new state object with one value changed, leaving the original untouched.

Encoding for sharing

Section titled “Encoding for sharing”

encodeState(state) produces a compact, URL-safe string containing only the values that differ from the defaults, so a shared link stays short even for a heavily customized theme. decodeState(str) reverses this, and tolerates garbage input by falling back to defaultState() rather than throwing.

Section titled “Sidebar IA helpers”

iaFromStarlightConfig and iaToStarlightConfig round-trip between Starlight’s sidebar config array and the editor’s internal tree shape, so the same data structure powers both the live site and the in-panel IA editor.