The StrictEventEmitter class that was defined in the socket.io-client
repository ([1]) is moved here, so we don't need to create an
intermediary class (Socket > StrictEventEmitter > Emitter) to get the
proper types.
As an additional benefit, the final bundle size should be decreased.
BREAKING CHANGE: we now use a named export instead of a default export
```js
// before
import Emitter from "@socket.io/component-emitter"
// after
import { Emitter } from "@socket.io/component-emitter"
```
[1]: a9e5b85580/lib/typed-events.ts
Removing the debug library and the debug calls from the final bundle is
unexpectedly quite hard.
Actually, there are several solutions, each with its own pro and cons:
> use webpack-remove-debug (our previous solution)
Pro: works well, even with ESM imports with a little hack
```js
import debugModule from "debug"; // debug()
const debug = debugModule("my-library"); // debug()
debug("hello world");
```
Cons: only for webpack
See also: https://github.com/johngodley/webpack-remove-debug
> NODE_ENV variable
```js
import debugModule from "debug";
let debug = () => {}
if (process.env.NODE_ENV !== "production") {
debug = debugModule("my-library");
}
```
Pro: the `debug()` calls are properly removed when bundling for
production
Cons: some bundlers leave the debug library in the bundle, even if it
is not called (for example, rollup needs an additional
"moduleSideEffects: true")
Reference: https://rollupjs.org/guide/en/#treeshake
> dynamic import
```js
let debug = () => {}
if (process.env.NODE_ENV !== "production") {
import("debug").then(debugModule => {
debug = debugModule.default("my-library");
});
}
```
Pro: the sanest solution, which allows to use debug in development
Cons: will likely break some bundlers due to the dynamic import (for
example, not supported for UMD bundles)
> browser field
```json
{
"browser": {
"debug": "./noop.js"
}
}
```
Pro: the safest solution from a compatibility point of view
Cons: some bundlers leave the noop debug calls, even after minification
> remove debug from the source code
We could also remove the debug calls, but the ability to turn them with
a single env variable on is quite appealing (at least in a Node.js
environment):
```
DEBUG=* node index.js
```
> dual packaging (our selected solution)
We provide two ESM builds, one with debug and one without.
Pros:
- no tricky configuration for bundlers
- debug logs are still available in Node.js
Cons:
- no more debug logs in the browser
We will go with the latest solution for now, until there is a better
alternative.
This change allows us to:
- reduce the size of the bundle
- provide an ESM bundle (for usage in <script type="module">)
BREAKING CHANGE: due to how default export works with ES modules, we
have removed the default export of the library, which means the
following code:
```js
require("engine.io-client")(...);
```
will not work anymore. The named export must be used instead:
```js
const { Socket } = require("engine.io-client);
// or import { Socket } from "engine.io-client";
const socket = new Socket(...);
```
Note: the UMD build still exposes a function though:
```html
<script src="/path/to/engine.io.js"></script>
<script>
const socket = eio(...);
</script>
```
Note: webpack is still used with zuul because of the custom builder
(zuul-builder-webpack)
This allows to control the behavior of mocked timers (@sinonjs/fake-timers),
depending on the value of the "useNativeTimers" option:
- true: use native setTimeout function
- false (default): use classic timers, that may be mocked
Related: 5d1d5bea11
The parser now returns the TypedArray object instead of the underlying
array buffer, so its offset and length are now taken in account (which
is the behavior of the classic WebSocket implementation).
Notes:
- this was already the case for the Node.js implementation
- in v3, the TypedArray object was always converted to an array buffer
because a byte was added at the beginning ("message" type)
- we could also have used "data.slice().buffer", but it would have
resulted in the copy of the buffer
Related:
- https://github.com/socketio/engine.io-parser/issues/122
- https://github.com/socketio/engine.io-client/issues/677
