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A modern runtime for JavaScript and TypeScript.
https://deno.com/
04ba709b6e
Currently fast ops will always check for the alignment of a TypedArray when getting a slice out of them. A match is then done to ensure that some slice was received and if not a fallback will be requested. For Uint8Arrays (and WasmMemory which is equivalent to a Uint8Array) the alignment will always be okay. Rust probably optimises this away for the most part (since the Uint8Array check is `x % 1 != 0`), but what it cannot optimise away is the fast ops path's request for fallback options parameter. The extra parameter's cost is likely negligible but V8 will need to check if a fallback was requested and prepare the fallback call just in case it was. In the future the lack of a fallback may also enable V8 to much better optimise the result handling. For V8 created buffers, it seems like all buffers are actually always guaranteed to be properly aligned: All buffers seem to always be created 8-byte aligned, and creating a 32 bit array or 64 bit array with a non-aligned offset from an ArrayBuffer is not allowed. Unfortunately, Deno FFI cannot give the same guarantees, and it is actually possible for eg. 32 bit arrays to be created unaligned using it. These arrays work fine (at least on Linux) so it seems like this is not illegal, it just means that we cannot remove the alignment checking for 32 bit arrays. |
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.cargo | ||
.devcontainer | ||
.github | ||
bench_util | ||
cli | ||
core | ||
ext | ||
lockfile | ||
ops | ||
runtime | ||
serde_v8 | ||
test_ffi | ||
test_napi | ||
test_util | ||
third_party@17e31cec93 | ||
tools | ||
.dlint.json | ||
.dprint.json | ||
.editorconfig | ||
.gitattributes | ||
.gitignore | ||
.gitmodules | ||
.rustfmt.toml | ||
Cargo.lock | ||
Cargo.toml | ||
LICENSE.md | ||
README.md | ||
Releases.md | ||
rust-toolchain.toml |
Deno
Deno is a simple, modern and secure runtime for JavaScript and TypeScript that uses V8 and is built in Rust.
Features
- Secure by default. No file, network, or environment access, unless explicitly enabled.
- Supports TypeScript out of the box.
- Ships only a single executable file.
- Built-in utilities.
- Set of reviewed standard modules that are guaranteed to work with Deno.
Install
Shell (Mac, Linux):
curl -fsSL https://deno.land/install.sh | sh
PowerShell (Windows):
irm https://deno.land/install.ps1 | iex
Homebrew (Mac):
brew install deno
Chocolatey (Windows):
choco install deno
Scoop (Windows):
scoop install deno
Build and install from source using Cargo:
cargo install deno --locked
See deno_install and releases for other options.
Getting Started
Try running a simple program:
deno run https://deno.land/std/examples/welcome.ts
Or a more complex one:
const listener = Deno.listen({ port: 8000 });
console.log("http://localhost:8000/");
for await (const conn of listener) {
serve(conn);
}
async function serve(conn: Deno.Conn) {
for await (const { respondWith } of Deno.serveHttp(conn)) {
respondWith(new Response("Hello world"));
}
}
You can find a deeper introduction, examples, and environment setup guides in the manual.
The complete API reference is available at the runtime documentation.
Contributing
We appreciate your help!
To contribute, please read our contributing instructions.