The structured clone algorithm copies complex JavaScript objects. It is used internally when invoking structuredClone(), to transfer data between Workers via postMessage(), storing objects with IndexedDB, or copying objects for other APIs.
It clones by recursing through the input object while maintaining a map of previously visited references, to avoid infinitely traversing cycles.
Function objects cannot be duplicated by the structured clone algorithm; attempting to throws a DataCloneError exception.DataCloneError exception.lastIndex property of RegExp objects is not preserved.ArrayArrayBufferBooleanDataViewDateError types (but see Error types below).MapNumberObject objects: but only plain objects (e.g., from object literals).symbol.RegExp: but note that lastIndex is not preserved.SetStringTypedArrayFor Error types, the error name must be one of: Error, EvalError, RangeError, ReferenceError, SyntaxError, TypeError, URIError (or will be set to "Error").
Browsers must serialize the properties name and message, and are expected to serialize other "interesting" properties of the errors such as stack, cause, etc.
AggregateError support is expected to be added to the specification in whatwg/html#5749 (and is already supported in some browsers).
AudioDataBlobCropTargetCryptoKeyDOMException: browsers must serialize the properties name and message. Other attributes may also be serialized/cloned.DOMMatrixDOMMatrixReadOnlyDOMPointDOMPointReadOnlyDOMQuadDOMRectDOMRectReadOnlyEncodedAudioChunkEncodedVideoChunkFencedFrameConfigFileFileListFileSystemDirectoryHandleFileSystemFileHandleFileSystemHandleGPUCompilationInfoGPUCompilationMessageGPUPipelineErrorImageBitmapImageDataRTCCertificateRTCEncodedAudioFrameRTCEncodedVideoFrameVideoFrameWebTransportErrorNote: Serializable objects are marked up in Web IDL files with the attribute [Serializable].