wasmparser

Simple streamable WebAssembly binary parser.

Test

Compiling Code

npm run build

Examples

See the examples/ folder.

Running Tests

npm test

Creating Tests

Place a .wasm and an associated .wasm.out file in the test directory. The testing harness will compare the parsing output of the .wasm file against the .wasm.out file. You can use the npm test update command to automatically create a .out files. This is useful if you have made a change that affects the tests.

Changelog

2.0.0 (2020-06-10)

Bug Fixes

• print data section entries in a single line (e2aa667)

Features

• remove type section from disassembly (d61d67d), closes #56

BREAKING CHANGES

• Disassembly output will no longer print all the types in the beginning by default.

The type section can be reconstructed from the implicit type information in the remainder of the disassembly, and is generally just cognitive overhead for developers, especially in the browser DevTools (see https://crbug.com/1092763 for relevant downstream issue in Chromium DevTools). Relying on the implicit type information is far more readable for humans and also avoids the need to dump all the types in the beginning, which take up precious space since both Chromium and Firefox DevTools limit the number of lines that are displayed for large Wasm modules.

This adds a skipTypes option to WasmDisassembler instances, which can be used to restore the old behavior. By default this option is set to true.

This includes a fix to call_indirect and return_call_indirect, where we had previously refered to the type by name, and now we use the abbreviated form for printing types as well [1].