96 lines
4.4 KiB
Markdown
96 lines
4.4 KiB
Markdown
# structuredClone polyfill
|
|
|
|
[](https://www.npmjs.com/package/@ungap/structured-clone) [](https://github.com/ungap/structured-clone/actions) [](https://coveralls.io/github/ungap/structured-clone?branch=main)
|
|
|
|
An env agnostic serializer and deserializer with recursion ability and types beyond *JSON* from the *HTML* standard itself.
|
|
|
|
* [Supported Types](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm#supported_types)
|
|
* *not supported yet*: Blob, File, FileList, ImageBitmap, ImageData, and ArrayBuffer, but typed arrays are supported without major issues, but u/int8, u/int16, and u/int32 are the only safely suppored (right now).
|
|
* *not possible to implement*: the `{transfer: []}` option can be passed but it's completely ignored.
|
|
* [MDN Documentation](https://developer.mozilla.org/en-US/docs/Web/API/structuredClone)
|
|
* [Serializer](https://html.spec.whatwg.org/multipage/structured-data.html#structuredserializeinternal)
|
|
* [Deserializer](https://html.spec.whatwg.org/multipage/structured-data.html#structureddeserialize)
|
|
|
|
Serialized values can be safely stringified as *JSON* too, and deserialization resurrect all values, even recursive, or more complex than what *JSON* allows.
|
|
|
|
|
|
### Examples
|
|
|
|
Check the [100% test coverage](./test/index.js) to know even more.
|
|
|
|
```js
|
|
// as default export
|
|
import structuredClone from '@ungap/structured-clone';
|
|
const cloned = structuredClone({any: 'serializable'});
|
|
|
|
// as independent serializer/deserializer
|
|
import {serialize, deserialize} from '@ungap/structured-clone';
|
|
|
|
// the result can be stringified as JSON without issues
|
|
// even if there is recursive data, bigint values,
|
|
// typed arrays, and so on
|
|
const serialized = serialize({any: 'serializable'});
|
|
|
|
// the result will be a replica of the original object
|
|
const deserialized = deserialize(serialized);
|
|
```
|
|
|
|
#### Global Polyfill
|
|
Note: Only monkey patch the global if needed. This polyfill works just fine as an explicit import: `import structuredClone from "@ungap/structured-clone"`
|
|
```js
|
|
// Attach the polyfill as a Global function
|
|
import structuredClone from "@ungap/structured-clone";
|
|
if (!("structuredClone" in globalThis)) {
|
|
globalThis.structuredClone = structuredClone;
|
|
}
|
|
|
|
// Or don't monkey patch
|
|
import structuredClone from "@ungap/structured-clone"
|
|
// Just use it in the file
|
|
structuredClone()
|
|
```
|
|
|
|
**Note**: Do not attach this module's default export directly to the global scope, whithout a conditional guard to detect a native implementation. In environments where there is a native global implementation of `structuredClone()` already, assignment to the global object will result in an infinite loop when `globalThis.structuredClone()` is called. See the example above for a safe way to provide the polyfill globally in your project.
|
|
|
|
### Extra Features
|
|
|
|
There is no middle-ground between the structured clone algorithm and JSON:
|
|
|
|
* JSON is more relaxed about incompatible values: it just ignores these
|
|
* Structured clone is inflexible regarding incompatible values, yet it makes specialized instances impossible to reconstruct, plus it doesn't offer any helper, such as `toJSON()`, to make serialization possible, or better, with specific cases
|
|
|
|
This module specialized `serialize` export offers, within the optional extra argument, a **lossy** property to avoid throwing when incompatible types are found down the road (function, symbol, ...), so that it is possible to send with less worrying about thrown errors.
|
|
|
|
```js
|
|
// as default export
|
|
import structuredClone from '@ungap/structured-clone';
|
|
const cloned = structuredClone(
|
|
{
|
|
method() {
|
|
// ignored, won't be cloned
|
|
},
|
|
special: Symbol('also ignored')
|
|
},
|
|
{
|
|
// avoid throwing
|
|
lossy: true,
|
|
// avoid throwing *and* looks for toJSON
|
|
json: true
|
|
}
|
|
);
|
|
```
|
|
|
|
The behavior is the same found in *JSON* when it comes to *Array*, so that unsupported values will result as `null` placeholders instead.
|
|
|
|
#### toJSON
|
|
|
|
If `lossy` option is not enough, `json` will actually enforce `lossy` and also check for `toJSON` method when objects are parsed.
|
|
|
|
Alternative, the `json` exports combines all features:
|
|
|
|
```js
|
|
import {stringify, parse} from '@ungap/structured-clone/json';
|
|
|
|
parse(stringify({any: 'serializable'}));
|
|
```
|