I'm trying some Wasm! I needed to test a few things:

• Can I compile WASM in the browser?
• Do I understand the binary format?

So I made this Wasm "compiler" where you write out the data in hexadecimal. It ignores every character that isn't 0-9 or a-f (case insensitive), so you can use some spacing. I also made it so you can put comments in regular parentheses ().

The header bytes (magic and version) are automatically added.

If it compiles successfully, it'll tell you what the exported functions are. Otherwise you'll need to check the console etc.

To call the function, you'd call wasm_module.instance.exports.{your function} in the console.

(-- types section --) 01 (of 7 bytes with 1 type) 07 01 (it's a function that takes 2 i32s and returns 1 i32) 60 02 7f 7f 01 7f (-- functions section --) 03 (2 bytes, 1 function) 02 01 (it's the first type in the previous list) 00 (-- export --) 07 (bytes and export size) 07 01 ( name is 3 characters: 'add') 03 61 64 64 ( function code, index) 00 00 (-- code section --) 0A ( byte size and number of code blocks) 0a 01 (function size and locals vector) 08 00 (get the parameters, add them, return, and end) 20 00 20 01 6a 0f 0b

Compile