/formkit-core-skilld

Schema and compiler

Core ships the schema types and the expression compiler; rendering lives in @formkit/vue / @formkit/react (FormKitSchemaContext, dist/index.d.mts:318-325).

Schema node types

FormKitSchemaNode union (dist/index.d.mts:331):

Common props on schema nodes (FormKitSchemaProps, dist/index.d.mts:243-250): children, key, if, for (a FormKitListStatement tuple [value, key?, list]), bind, meta.

Attribute values accept condition objects (FormKitSchemaAttributesCondition: { if, then, else? }, dist/index.d.mts:277-281).

Type guards and sugar

import { isDOM, isComponent, isConditional, isSugar, sugar } from '@formkit/core'

if (isSugar(node)) node = sugar(node)   // $formkit → $cmp: 'FormKit'

sugar() rewrites { $formkit: 'text', label: X } into a FormKitSchemaComponent with props spread and moves if / for / children / bind up (dist/index.mjs:1526-1551). Guards: dist/index.d.mts:388-438.

FormKitSectionsSchema maps section names to FormKitSchemaNodeExtension values (partial nodes or null to unset) — the shape input definitions accept for section overrides (dist/index.d.mts:333-378).

Compiler

compile(expr) parses a $-token expression into one function (dist/index.d.mts:2194-2217):

const condition = compile("$name == 'bob'").provide((tokens) => {
  // tokens is the array of required token names, e.g. ['name']
  return { name: () => nameRef.value }  // every value MUST be a function
})
condition()  // false

Grammar (dist/index.mjs:1574-1598,1701-1710):

• Token references: $foo, nested $foo.bar, calls $fn(...) (parenthesized $-prefixed operands become function tokens; tails bind this, dist/index.mjs:1552-1567).
• Operators by precedence: && || → == != === !== > < >= <= → + - → * / %.
• String literals in single or double quotes with \ escapes (dist/index.mjs:1660-1700).
• A leading operator or trailing operator is a compile error (codes 103/104, dist/index.mjs:1714-1719).

Compiled output type is FormKitCompilerOutput: call with a tokens object to evaluate; .provide(callback) injects token resolvers (dist/index.d.mts:2182-2192).

In schema strings, $: prefixes mark compiled expressions; expr.startsWith('$:') is stripped before parsing (dist/index.mjs:1831). The rendering adapter supplies token values: $_value (live, non-debounced), $value (committed), $handlers, $attrs, and node props directly ($label, $type, …) (https://formkit.com/essentials/custom-inputs).