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Docs.md
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@ -1,18 +1,28 @@
# Deno Docs
# Deno Documentation
## Disclaimer
A word of caution: Deno is very much under development. We encourage brave early
adopters, but expect bugs large and small. The API is subject to change without
notice.
[Bug reports](https://github.com/denoland/deno/issues) do help!
## Install
Deno works on OSX, Linux, and Windows. We provide binary download scripts:
Deno works on OSX, Linux, and Windows. Deno is a single binary executable. It
has no external dependencies.
With Python:
[deno_install](https://github.com/denoland/deno_install) provides convenience
scripts to download and install the binary.
Using Python:
```
curl -sSf https://raw.githubusercontent.com/denoland/deno_install/master/install.py | python
```
See also [deno_install](https://github.com/denoland/deno_install).
With PowerShell:
Or using PowerShell:
```powershell
iex (iwr https://raw.githubusercontent.com/denoland/deno_install/master/install.ps1)
@ -22,10 +32,15 @@ _Note: Depending on your security settings, you may have to run
`Set-ExecutionPolicy RemoteSigned -Scope CurrentUser` first to allow downloaded
scripts to be executed._
Deno can also be installed manually, by downloading a tarball or zip file at
[github.com/denoland/deno/releases](https://github.com/denoland/deno/releases).
These packages contain just a single executable file. You will have to set the
executable bit on Mac and Linux.
Try it:
```
> deno http://deno.land/thumb.ts
> deno https://deno.land/thumb.ts
```
## API Reference
@ -34,58 +49,186 @@ To get an exact reference of deno's runtime API, run the following in the
command line:
```
deno --types
> deno --types
```
In case you don't have it installed yet, but are curious, here is an out-of-date
copy of the output: https://gist.github.com/78855aeeaddeef7c1fce0aeb8ffef8b2
Or see the [doc website](https://deno.land/typedoc/index.html).
(We do not yet have an HTML version of this. See
https://github.com/denoland/deno/issues/573)
If you are embedding deno in a Rust program, see
[the rust docs](https://deno.land/rustdoc/deno/index.html).
## Examples
## Tutorial
### Example: An implementation of the unix "cat" program
### An implementation of the unix "cat" program
The copy here is actually zero-copy. That is, it reads data from the socket and
writes it back to it without ever calling a memcpy() or similar.
In this program each command-line argument is assumed to be a filename, the file
is opened, and printed to stdout.
```ts
import * as deno from "deno";
for (let i = 1; i < deno.args.length; i++) {
(async () => {
for (let i = 1; i < deno.args.length; i++) {
let filename = deno.args[i];
let file = await deno.open(filename);
await deno.copy(deno.stdout, file);
}
file.close();
}
})();
```
### Example: A TCP Server echo server
The `copy()` function here actually makes no more than the necessary kernel ->
userspace -> kernel copies. That is, the same memory from which data is read
from the file, is written to stdout. This illustrates a general design goal for
I/O streams in Deno.
The copy here is actually zero-copy. That is, it reads data from the socket and
writes it back to it without ever calling a memcpy() or similar.
Try the program:
```
> deno https://deno.land/x/examples/cat.ts /etc/passwd
```
### TCP echo server
This is an example of a simple server which accepts connections on port 8080,
and returns to the client anything it sends.
```ts
import { listen, copy } from "deno";
const listener = listen("tcp", ":8080");
while (true) {
(async () => {
const addr = "0.0.0.0:8080";
const listener = listen("tcp", addr);
console.log("listening on", addr);
while (true) {
const conn = await listener.accept();
copy(conn, conn);
}
// TODO top level await doesn't work yet.
}
})();
```
### Example: Url imports
When this program is started, the user is prompted for permission to listen on
the network:
```
> deno https://deno.land/x/examples/echo_server.ts
deno requests network access to "listen". Grant? [yN] y
listening on 0.0.0.0:8080
```
For security reasons, deno does not allow programs to access the network without
explicit permission. To avoid the console prompt, use a command-line flag:
```
> deno https://deno.land/x/examples/echo_server.ts --allow-net
```
To test it, try sending a HTTP request to it by using curl. The request gets
written directly back to the client.
```
> curl http://localhost:8080/
GET / HTTP/1.1
Host: localhost:8080
User-Agent: curl/7.54.0
Accept: */*
```
It's worth noting that like the `cat.ts` example, the `copy()` function here
also does not make unnecessary memory copies. It receives a packet from the
kernel and sends back, without further complexity.
### Linking to third party code
In the above examples, we saw that Deno could execute scripts from URLs. Like
browser JavaScript, Deno can import libraries directly from URLs. This example
uses a URL to import a test runner library:
```ts
import { printHello } from "https://raw.githubusercontent.com/denoland/deno/master/tests/subdir/print_hello.ts";
printHello();
import { test, assertEqual } from "https://deno.land/x/testing/testing.ts";
test(function t1() {
assertEqual("hello", "hello");
});
test(function t2() {
assertEqual("world", "world");
});
```
The next time you import the same file from same uri it will use the cached
resource instead of downloading it again.
Try running this:
## How to Profile Deno
```
> deno https://deno.land/x/examples/example_test.ts
Compiling /Users/rld/src/deno_examples/example_test.ts
Downloading https://deno.land/x/testing/testing.ts
Downloading https://deno.land/x/testing/util.ts
Compiling https://deno.land/x/testing/testing.ts
Compiling https://deno.land/x/testing/util.ts
running 2 tests
test t1
... ok
test t2
... ok
test result: ok. 2 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
```
Note that we did not have to provide the `--allow-net` flag for this program,
and yet it accessed the network. The runtime has special access to download
imports and cache them to disk.
Deno caches remote imports in a special directory specified by the `$DENO_DIR`
environmental variable. It default to `$HOME/.deno` if `$DENO_DIR` is not
specified. The next time you run the program, no downloads will be made. If the
program hasn't changed, it won't be recompiled either.
**But what if `https://deno.land/` goes down?** Relying on external servers is
convenient for development but brittle in production. Production software should
always bundle its dependencies. In Deno this is done by checking the `$DENO_DIR`
into your source control system, and specifying that path as the `$DENO_DIR`
environmental variable at runtime.
**How do you import to a specific version?** Simply specify the version in the
URL. For example, this URL fully specifies the code being run:
`https://unpkg.com/liltest@0.0.5/dist/liltest.js`. Combined with the
aforementioned technique of setting `$DENO_DIR` in production to stored code,
one can fully specify the exact code being run, and execute the code without
network access.
**It seems unwieldy to import URLs everywhere. What if one of the URLs links to
a subtly different version of a library? Isn't it error prone to maintain URLs
everywhere in a large project?** The solution is to import and re-export your
external libraries in a central `package.ts` file (which serves the same purpose
as Node's `package.json` file). For example, let's say you were using the above
testing library across a large project. Rather than importing
`"https://deno.land/x/testing/testing.ts"` everywhere, you could create a
`package.ts` file the exports the third-party code:
```ts
export { test, assertEqual } from "https://deno.land/x/testing/testing.ts";
```
And throughout project one can import from the `package.ts` and avoid having
many references to the same URL:
```ts
import { test, assertEqual } from "./package.ts";
```
This design circumvents a plethora of complexity spawned by package management
software, centralized code repositories, and superfluous file formates.
## Useful command line flags
V8 has many many command-line flags, that you can see with `--v8-options`. Here
are a few particularly useful ones:
```
--async-stack-traces
```
## How to Profile deno
```sh
# Make sure we're only building release.
@ -108,11 +251,11 @@ isolate-0x7fad98242400-v8.log
### Prerequisites:
To ensure reproducible builds, Deno has most of its dependencies in a git
To ensure reproducible builds, deno has most of its dependencies in a git
submodule. However, you need to install separately:
1. [Rust](https://www.rust-lang.org/en-US/install.html)
2. [Node](http://nodejs.org/)
2. [Node](https://nodejs.org/)
3. Python 2.
[Not 3](https://github.com/denoland/deno/issues/464#issuecomment-411795578).
4. [ccache](https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Build_Instructions/ccache)
@ -175,7 +318,7 @@ Environment variables: `DENO_BUILD_MODE`, `DENO_BUILD_PATH`, `DENO_BUILD_ARGS`,
### Internal: libdeno API.
Deno's privileged side will primarily be programmed in Rust. However there will
deno's privileged side will primarily be programmed in Rust. However there will
be a small C API that wraps V8 to 1) define the low-level message passing
semantics, 2) provide a low-level test target, 3) provide an ANSI C API binding
interface for Rust. V8 plus this C API is called "libdeno" and the important
@ -239,9 +382,9 @@ V8's GC will lead to difficult contention problems down the road.
The V8Worker2 binding/concept is being ported to a new C++ library called
libdeno. libdeno will include the entire JS runtime as a V8 snapshot. It still
follows the message passing paradigm. Rust will be bound to this library to
implement the privileged part of Deno. See deno2/README.md for more details.
implement the privileged part of deno. See deno2/README.md for more details.
V8 Snapshots allow Deno to avoid recompiling the TypeScript compiler at startup.
V8 Snapshots allow deno to avoid recompiling the TypeScript compiler at startup.
This is already working.
When the rewrite is at feature parity with the Go prototype, we will release
@ -253,20 +396,18 @@ https://github.com/denoland/deno/tree/golang
https://www.youtube.com/watch?v=M3BM9TB-8yA
http://tinyclouds.org/jsconf2018.pdf
https://tinyclouds.org/jsconf2018.pdf
### 2007-2017 / Prehistory
https://github.com/ry/v8worker
http://libuv.org/
https://libuv.org/
http://tinyclouds.org/iocp-links.html
https://tinyclouds.org/iocp-links.html
https://nodejs.org/
https://github.com/nodejs/http-parser
http://tinyclouds.org/libebb/
https://en.wikipedia.org/wiki/Merb
https://tinyclouds.org/libebb/

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website/index.html
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@ -2,20 +2,23 @@
<!DOCTYPE html>
<html>
<head>
<title>deno</title>
<title>Deno</title>
<link rel="stylesheet" href="https://unpkg.com/c3@0.6.7/c3.min.css">
<link rel="stylesheet" href="style.css">
<meta content='width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0' name='viewport' />
</head>
<body>
<main>
<h1>deno</h1>
<h1>Deno</h1>
<p>Deno is program for executing JavaScript and TypeScript outside of the
web browser.
<p> <a href="https://github.com/denoland/deno">github.com/denoland/deno</a>
<p> <a href="https://github.com/denoland/deno/blob/master/Docs.md">Intro</a>
<p> <a href="typedoc/index.html">TypeScript API</a>
<p> <a href="rustdoc/deno/index.html">Rust API</a>
<p> <a href="https://github.com/denoland/deno/blob/master/Docs.md">Documentation</a>
<p> <a href="typedoc/index.html">API Reference</a>
<h2>Execution time</h2>
This shows how much time total it takes to run a few simple deno programs: