mirror of
https://github.com/denoland/deno.git
synced 2024-11-30 16:40:57 -05:00
163 lines
3.5 KiB
Markdown
163 lines
3.5 KiB
Markdown
# Deno Node.js compatibility
|
|
|
|
This module is meant to have a compatibility layer for the
|
|
[Node.js standard library](https://nodejs.org/docs/latest/api/).
|
|
|
|
**Warning**: Any function of this module should not be referred anywhere in the
|
|
Deno standard library as it's a compatibility module.
|
|
|
|
## Supported modules
|
|
|
|
- [x] assert
|
|
- [x] assert/strict _partly_
|
|
- [x] async_hooks _partly_
|
|
- [x] buffer
|
|
- [x] child_process _partly_
|
|
- [x] cluster _partly_
|
|
- [x] console _partly_
|
|
- [x] constants _partly_
|
|
- [x] crypto _partly_
|
|
- [x] dgram _partly_
|
|
- [x] diagnostics_channel _partly_
|
|
- [x] dns _partly_
|
|
- [x] events
|
|
- [x] fs _partly_
|
|
- [x] fs/promises _partly_
|
|
- [x] http _partly_
|
|
- [ ] http2
|
|
- [x] https _partly_
|
|
- [x] inspector _partly_
|
|
- [x] module
|
|
- [x] net
|
|
- [x] os _partly_
|
|
- [x] path
|
|
- [x] path/posix
|
|
- [x] path/win32
|
|
- [x] perf_hooks
|
|
- [x] process _partly_
|
|
- [x] punycode
|
|
- [x] querystring
|
|
- [x] readline
|
|
- [x] repl _partly_
|
|
- [x] stream
|
|
- [x] stream/promises
|
|
- [x] stream/web _partly_
|
|
- [x] string_decoder
|
|
- [x] sys
|
|
- [x] timers
|
|
- [x] timers/promises
|
|
- [ ] tls
|
|
- [ ] trace_events
|
|
- [x] tty _partly_
|
|
- [x] url
|
|
- [x] util _partly_
|
|
- [x] util/types _partly_
|
|
- [ ] v8
|
|
- [x] vm _partly_
|
|
- [x] wasi
|
|
- [ ] webcrypto
|
|
- [x] worker_threads
|
|
- [ ] zlib
|
|
|
|
* [x] node globals _partly_
|
|
|
|
### Deprecated
|
|
|
|
These modules are deprecated in Node.js and will probably not be polyfilled:
|
|
|
|
- domain
|
|
- freelist
|
|
|
|
### Experimental
|
|
|
|
These modules are experimental in Node.js and will not be polyfilled until they
|
|
are stable:
|
|
|
|
- diagnostics_channel
|
|
- async_hooks
|
|
- policies
|
|
- trace_events
|
|
- wasi
|
|
- webcrypto
|
|
|
|
## CommonJS modules loading
|
|
|
|
`createRequire(...)` is provided to create a `require` function for loading CJS
|
|
modules. It also sets supported globals.
|
|
|
|
```ts
|
|
import { createRequire } from "node:module";
|
|
|
|
const require = createRequire(import.meta.url);
|
|
// Loads native module polyfill.
|
|
const path = require("path");
|
|
// Loads extensionless module.
|
|
const cjsModule = require("./my_mod");
|
|
// Visits node_modules.
|
|
const leftPad = require("left-pad");
|
|
```
|
|
|
|
## Contributing
|
|
|
|
### Setting up the test runner and running tests
|
|
|
|
See [tools/node_compat/README.md](../../../tools/node_compat/README.md).
|
|
|
|
### Best practices
|
|
|
|
When converting from promise-based to callback-based APIs, the most obvious way
|
|
is like this:
|
|
|
|
```ts, ignore
|
|
promise.then((value) => callback(null, value)).catch(callback);
|
|
```
|
|
|
|
This has a subtle bug - if the callback throws an error, the catch statement
|
|
will also catch _that_ error, and the callback will be called twice. The correct
|
|
way to do it is like this:
|
|
|
|
```ts, ignore
|
|
promise.then((value) => callback(null, value), callback);
|
|
```
|
|
|
|
The second parameter of `then` can also be used to catch errors, but only errors
|
|
from the existing promise, not the new one created by the callback.
|
|
|
|
If the Deno equivalent is actually synchronous, there's a similar problem with
|
|
try/catch statements:
|
|
|
|
```ts, ignore
|
|
try {
|
|
const value = process();
|
|
callback(null, value);
|
|
} catch (err) {
|
|
callback(err);
|
|
}
|
|
```
|
|
|
|
Since the callback is called within the `try` block, any errors from it will be
|
|
caught and call the callback again.
|
|
|
|
The correct way to do it is like this:
|
|
|
|
```ts, ignore
|
|
let err, value;
|
|
try {
|
|
value = process();
|
|
} catch (e) {
|
|
err = e;
|
|
}
|
|
if (err) {
|
|
callback(err); // Make sure arguments.length === 1
|
|
} else {
|
|
callback(null, value);
|
|
}
|
|
```
|
|
|
|
It's not as clean, but prevents the callback being called twice.
|
|
|
|
### Remaining Tests
|
|
|
|
Node compatibility can be measured by how many native Node tests pass. If you'd
|
|
like to know what you can work on, check out the list of Node tests remaining
|
|
[here](../../../tools/node_compat/TODO.md).
|