eszip

The eszip format lets you losslessly serialize an ECMAScript module graph (represented by deno_graph::ModuleGraph) into a single compact file.

The eszip file format is designed to be compact and streaming capable. This allows for efficient loading of large ECMAScript module graphs.

Examples

Creating an eszip

cargo run --example eszip_builder https://deno.land/std/http/file_server.ts file_server.eszip2

Viewing the contents of an eszip

cargo run --example eszip_viewer file_server.eszip2

Loading the eszip into V8

cargo run --example eszip_load file_server.eszip2 https://deno.land/std/http/file_server.ts

File format

The file format looks as follows:

Eszip:
| Magic (8) | Header size (4) | Header (n) | Header hash (32) | Sources size (4) | Sources (n) | SourceMaps size (4) | SourceMaps (n) |

Header:
( | Specifier size (4) | Specifier (n) | Entry type (1) | Entry (n) | )*

Entry (redirect):
| Specifier size (4) | Specifier (n) |

Entry (module):
| Source offset (4) | Source size (4) | SourceMap offset (4) | SourceMap size (4) | Module type (1) |

Sources:
( | Source (n) | Hash (32) | )*

SourceMaps:
( | SourceMap (n) | Hash (32) | )*

There is one optimization for empty source / source map entries. If both the offset and size are set to 0, no entry and no hash is present in the data sections for that module.

Development

rustup target add wasm32-unknown-unknown
cargo install wasm-bindgen-cli
deno install --unstable -A -f -n wasmbuild https://raw.githubusercontent.com/denoland/wasmbuild/7b714ee749e4dc1e4ed1bc6f7258235a6c289aec/main.ts
brew install binaryen

When opening a PR make sure to rebuild WASM by running:

make release

Troubleshooting

Errors like:

thread 'main' panicked at 'remaining data [20, 10, 85, 105, 110, 116, 56, 65, 114, 114, 97, 121]', /.cargo/registry/src/github.com-1ecc6299db9ec823/wasm-bindgen-cli-support-0.2.78/src/descriptor.rs:111:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
wasm-bindgen failed
make: *** [build] Error 1

mean that wasm-bindgen-cli doesn't match version specified in Cargo.toml.

To fix it, run cargo install wasm-bindgen-cli --version VERSION where VERSION matches what's specified in Cargo.toml.