[Home](./index.md) > [puppeteer](./puppeteer.md) > [Protocol](./puppeteer.protocol.md) > [DOM](./puppeteer.protocol.dom.md) > [Node](./puppeteer.protocol.dom.node.md) > [systemId](./puppeteer.protocol.dom.node.systemid.md) ## Protocol.DOM.Node.systemId property `DocumentType`'s systemId. Signature: ```typescript systemId?: string; ```