This restores the possibility to import the bundle directly, without
getting the following error:
> [ERR_PACKAGE_PATH_NOT_EXPORTED]: Package subpath './dist/engine.io.min.js' is not defined by "exports"
On macOS the script was interpreted as the value of the `-i` option. It
will now use an empty extension for the `-i` option and the `-e` option
to specify the script.
Some bundlers (like vite) do not support having a "browser" field in a
nested package.json.
Note: the previous commit ([1]) fixed the resolution of the "browser"
field in the dev bundle, but the production bundle still failed.
Related: https://github.com/socketio/socket.io-client/issues/1504
[1]: 49719142f6
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
The "installTimerFunctions" method will also be used in the
`socket.io-client` package:
```
import { installTimerFunctions } from "engine.io-client/lib/util";
```
Note: we could also have put the method in its own library, but that
sounded a bit overkill
Related: https://github.com/socketio/socket.io-client/pull/1479
An immediate setTimeout was used to unblock the WebSocket write.
Unfortunately, this setTimeout can be throttled by browsers when the
tab is backgrounded.
This can lead to missed pong responses to server pings, which
eventually leads to disconnection.
Related: https://github.com/socketio/engine.io-client/issues/649
Since [1], the socket is now closed when receiving the "beforeunload"
event in the browser.
This change was meant to fix a discrepancy between Chrome and Firefox
when the user reloads/closes a browser tab: Firefox would close the
connection (and emit a "disconnect" event, at the Socket.IO level), but
not Chrome (see [2]).
But it also closes the connection when there is another "beforeunload"
handler, for example when the user is prompted "are you sure you want
to leave this page?".
Note: calling "stopImmediatePropagation()" was a possible workaround:
```js
window.addEventListener('beforeunload', (event) => {
event.preventDefault();
event.stopImmediatePropagation();
event.returnValue = 'are you sure you want to leave this page?';
});
```
This commit adds a "closeOnBeforeunload" option, which controls whether
a handler is registered for the "beforeunload" event.
Syntax:
```js
const socket = require('engine.io-client')('ws://localhost', {
closeOnBeforeunload: false // defaults to true
});
```
[1]: ed48b5dc34
[2]: https://github.com/socketio/socket.io/issues/3639
Related:
- https://github.com/socketio/engine.io-client/issues/661
- https://github.com/socketio/engine.io-client/issues/658
- https://github.com/socketio/socket.io-client/issues/1451
Reference: https://developer.mozilla.org/en-US/docs/Web/API/Window/beforeunload_event
In some cases, a "Transport not open" error could be thrown when the
transport was silently closed in the onbeforeunload event (added in
[1]).
To reproduce:
```js
window.addEventListener("unload", () => {
socket.write("...");
});
```
[1]: ed48b5dc34
Related: https://github.com/socketio/socket.io/issues/3838
With autoUnref set to true (default: false), the Engine.IO client will
allow the program to exit if there is no other active timer/socket in
the event system.
Note: the 'xmlhttprequest-ssl' package has been copied in the contrib/
directory, until the change is merged upstream
Related: https://github.com/socketio/engine.io-client/issues/653
