WebAssembly.Compile is disallowed on the main thread, if the buffer size is larger than 4KB

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I'm trying out a simple hello world WebAssembly example and I'm having trouble understanding an error I'm seeing in Chrome 59:

RangeError: WebAssembly.Compile is disallowed on the main thread, if the buffer size is larger than 4KB. Use WebAssembly.compile, or compile on a worker thread.

src/wasm/counter.wasm:13
  10 | let wa;
  11 | const make = source => {
  12 |   // buffer should already be set
> 13 |   return wa = new Module(buffer);
  14 | };
  15 | 
  16 | const WebAssemblyModule = function(deps = {

I've followed the steps in this tutorial, and I can build everything without error. I'm using create-react-app rewired with wasm-loader.

If I'm using my local build of the counter module I get the error I mentioned in the beginning. If I try and use a pre-built version (for example the one in this project) it works fine.

When I build my module, I'm using the same command as specified in the tutorial. The project with the working module has the same command listed in its README:

emcc counter.c -O1 -o counter.wasm -s WASM=1 -s SIDE_MODULE=1

Any idea what might be causing the error?

webassembly javascript
2 Answers

Create a URL object by Buffer, then use instantiateStreaming async method to load wasm.

const blob = new Blob([buffer], { type: "application/wasm" });
const url = URL.createObjectURL(blob);
wasm = await instantiateStreaming(fetch(url), {});
user_3341030
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