@napi-rs/wasm-tools
Documentation

API Reference

Version note. Only ModuleConfig and WasmModule.fromPath / fromFileWithConfig / emitWasm ship in the published 1.0.1. The collections, live handles, fromBuffer, buildFunction, instructions(), and the value constants below require ≥ 1.0.2 (not yet published). See Getting Started for details.

Everything is exported from the package root:

ts
import {
  WasmModule,
  ModuleConfig,
  ConstExpr,
  I32,
  I64,
  F32,
  F64,
  V128,
  FUNCREF,
  EXTERNREF,
  ANYREF,
  EQREF, // …and the rest of the reference-type constants
} from '@napi-rs/wasm-tools'

Core

Class What it is
WasmModule A parsed wasm module. Parse via fromBuffer / fromPath, edit through its collections, serialize with emitWasm / emitWasmFile; also buildFunction, gc, writeGraphvizDot, and the name / start / mainMemory accessors.
ModuleConfig Chainable parse-options builder (generateDwarf, generateNameSection, strictValidate, preserveCodeTransform, …); parse(bytes) returns a WasmModule.

Collections

Each hangs off a WasmModule getter, caches nothing, and shares .length / .items() / .getByIndex().

Class Module getter What it holds
WasmFunctions mod.functions Every function (imported + local); byName, delete.
WasmGlobals mod.globals Globals; byName, addLocal, delete.
WasmMemories mod.memories Memories; addLocal, delete.
WasmTables mod.tables Tables; mainFunctionTable, addLocal / addLocalWithInit, delete.
WasmTypes mod.types Type arena; add, find, addStruct / addArray / addComposite / addRecGroup.
WasmDataSegments mod.data Data segments; addPassive, addActive, delete.
WasmElements mod.elements Element segments; addFunctions, addExpressions, delete.
WasmTags mod.tags Exception-handling tags; add, delete.
WasmImports mod.imports Imports; find, addFunction / addMemory / addTable / addGlobal / addTag, delete.
WasmExports mod.exports Exports; byName, addFunction / addTable / addMemory / addGlobal / addTag, delete.
WasmLocals mod.locals Module-wide local arena; add.

Section façades

mod.producers and mod.customs are not arena-backed collections — they do not share the .length / .items() / .getByIndex() contract above. Each wraps a single module section with its own API:

Class Module getter API
WasmProducers mod.producers addLanguage / addProcessedBy / addSdk, fields(), clear().
WasmCustomSections mod.customs addRaw, removeRaw, list().

Handles (items)

A live handle to one item — its stable .index, mutable .name, a read-only kind, and typed cross-links back into the module.

Class What it is
WasmFunction One function: kind, ty(), instructions(), import().
WasmGlobal One global: ty, mutable, shared, kind, init(), import().
WasmMemory One memory: initial / maximum (bigint pages), shared, memory64, pageSizeLog2, import().
WasmTable One table: elementTy, initial / maximum (bigint entries), table64, init(), import().
WasmType One type: kind, params() / results() / structFields() / arrayElement(), supertype, recGroupMembers(), refNull().
WasmData One data segment: kind, value bytes, memory(), offset().
WasmElement One element segment: kind, itemsKind, table(), offset(), functionItems() / expressionItems().
WasmTag One exception tag: kind, ty(), import().
WasmImport One import: module / name, kind, typed func() / table() / memory() / global() / tag().
WasmExport One export: name, kind, typed func() / table() / memory() / global() / tag().
WasmLocal One local: ty (read only), name.

Values

Class What it is
ConstExpr A constant expression for initializers. Factory statics: i32, i64, f32, f64, v128, globalGet, refFunc, refNull; read kind.

Value-type constants

Numeric: I32, I64, F32, F64, V128.

Nullable reference types: FUNCREF, EXTERNREF, ANYREF, EQREF, I31REF, STRUCTREF, ARRAYREF, NULLREF, NULLFUNCREF, NULLEXTERNREF, EXNREF, NULLEXNREF.

Each is a ready-made ValType, so import { I32 } replaces writing { type: 'I32' } by hand.