Paste Transformer

The PasteTransformer converts complex HTML and Markdown payloads originating from standard OS ClipboardEvent buffers into strictly valid ProseMirror Transaction boundaries.

Constructor

new PasteTransformer(
  schema: Schema,
  extraMarkdownRules: MarkdownBlockRule[] = [],
  markdownParserTokens: Record<string, MarkdownParserTokenSpec> = {}
)

• schema: The compiled Prosemirror schema used to construct valid block nodes.
• extraMarkdownRules: Regex pattern rules injected by Custom Extensions to scrape plain text strings into rich layouts (e.g. matching --- to a Horizontal Rule).
• markdownParserTokens: CommonMark schema translations.

Methods

transform()

transform(clipboardData: DataTransfer, state: EditorState): Transaction | null

The central invocation function. Parses the DataTransfer using a prioritized fallback list:

1. text/html utilizing a sterilized DOM Parser.
2. text/plain utilizing prosemirror-markdown CommonMark.
3. text/plain utilizing legacy line-by-line fallback regex processing.
4. Normal insertText() string concatenation as an absolute last resort.

Utility Functions

cleanPastedHtml()

export function cleanPastedHtml(root: HTMLElement): void

An aggressive DOM sterilizer triggered prior to processing payload nodes.

• Discards style, meta, link garbage blocks.
• Unwraps Google Docs' proprietary <b id="docs-internal-guid..."> containers.
• Burns redundant empty <p> elements surrounding <hr> layouts.
• Trims non-schema CSS properties out of nested span [style] objects.