Limitations

Web browsers execute the WebAssembly (Wasm) bytecode in a sandboxed environment separated from the host. The sandboxed environment has some limitations, including

  • maximum of 4 GB because of the use of 32-bit indexes.

  • multithreading is still being standardized and implemented by browsers.

  • single instruction, multiple data (SIMD) is still being standardized and implemented by browsers.

  • can only escape the sandbox going through appropriate APIs.

Network

The biggest limitation for the end user is probably related with access to the internet that can happen using Fetch API or proxy.

Fetch API

The Wasm code uses the Fetch API directly and follows the same security of JavaScript running in the browser, for example Cross-Origin Resource Sharing (CORS).

Proxy

The Wasm code uses the Fetch API to contact a proxy server that is responsible to fulfill the access to the internet.

References