CODEWITHSUNDEEP
javascriptcemscriptenwebassembly
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Reputation: 91

Wasm: Uncaught (in promise) TypeError: Import #0 module="env" error: module is not an object or function Promise.then (async) (anonymous) @ (index):9

I'm new to emscripten and find it very hard... I have obligation to work on windows because i have to test .exe versions of my apps. I'm on windows 7.

I can compile wasm but javascript cannot read it. Here's my code.

C code:

char * HelloWorld ()
{
    return "Hello World !";
}

Emscripten command-line:

emcc hello.c -O2 -s ONLY_MY_CODE=1 -s WASM=1 -s SIDE_MODULE=1 -s EXPORTED_FUNCTIONS="['_HelloWorld']" -o hello.wasm

Wat result:

(module
  (type $t0 (func (result i32)))
  (type $t1 (func))
  (import "env" "memory" (memory $env.memory 256))
  (import "env" "memoryBase" (global $env.memoryBase i32))
  (func $_HelloWorld (export "_HelloWorld") (type $t0) (result i32)
    (get_global $env.memoryBase))
  (func $__post_instantiate (export "__post_instantiate") (type $t1)
    (set_global $g1
      (i32.add
        (get_global $env.memoryBase)
        (i32.const 16)))
    (set_global $g2
      (i32.add
        (get_global $g1)
        (i32.const 5242880))))
  (global $g1 (mut i32) (i32.const 0))
  (global $g2 (mut i32) (i32.const 0))
  (data (get_global $env.memoryBase) "Hello World !"))

Javascript:

importObject = {};

fetch('hello.wasm').then(response =>
  response.arrayBuffer()
).then(bytes =>
  WebAssembly.instantiate(bytes, importObject)
).then(results => {
  console.log("loaded");
});

Error message:

Uncaught (in promise) TypeError: Import #0 module="env" error: module is not an object or function
Promise.then (async)
(anonymous) @ (index):9

Can you tell me what's wrong in my code ?

Upvotes: 9

Views: 9268

Answers (2)

ruinb0w
ruinb0w

Reputation: 101

you should write importObject like this

const importObject = {
  env: {
    __memory_base: 0,
    __table_base: 0,
    memory: new WebAssembly.Memory({initial: 1})
  }
}

Upvotes: 5

Michael Cole
Michael Cole

Reputation: 16217

I think the challenge is this: WebAssembly isn't fully baked yet.

The examples show their loader from what looks like an NPM package. In that package, importObj is optional.

You and I are trying to use WebAssembly.instantiate() - I'm using a web worker.

So we need to pass a more complete imports - specifically an env with an abort methoed. Here's an example from https://webassembly.studio 's assemblyscript starter project:

main.html

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
</head>
<body style="background: #fff">
  <span id="container"></span>
  <script src="./main.js"></script>
</body>
</html>

main.js

WebAssembly.instantiateStreaming(fetch("../out/main.wasm"), {
  main: {
    sayHello() {
      console.log("Hello from WebAssembly!");
    }
  },
  env: {
    abort(_msg, _file, line, column) {
      console.error("abort called at main.ts:" + line + ":" + column);
    }
  },
}).then(result => {
  const exports = result.instance.exports;
  document.getElementById("container").textContent = "Result: " + exports.add(19, 23);
}).catch(console.error);

main.ts

declare function sayHello(): void;

sayHello();

export function add(x: i32, y: i32): i32 {
  return x + y;
}

Note the env.abort function in importObject

Upvotes: 6

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