js-string-builtins

(module
  (import "wasm:js-string" "fromCharCodeArray" (func $fromCharCodeArray (param (ref null $char-array)) (param i32) (param i32) (result (ref extern))))
  (type $char-array (array (mut i16)))

  (func (export "test")
    (result (ref extern))

      (call $fromCharCodeArray
        (array.new_fixed $char-array 3
          (i32.const 97)
          (i32.const 98)
          (i32.const 99)
        )
        (i32.const 0)
        (i32.const 3)
      )
  )
)

import { readFileSync } from "node:fs";
const wasmBuffer = readFileSync("hello.wasm");
const importObj = {}
const wasmModule = await WebAssembly.instantiate(wasmBuffer, importObj, { builtins: ['js-string'] });
const { test } = wasmModule.instance.exports;
const o = test();
console.log(o);

$ wasm-as --version
wasm-as version 117
$ node -v
v22.3.0

$ wasm-as -all hello.wat
$ node --experimental-wasm-imported-strings hello.mjs
abc