DOM.querySelector

{
  "name": "querySelector",
  "parameters": [
    {
      "name": "nodeId",
      "$ref": "NodeId",
      "description": "Id of the node to query upon."
    },
    {
      "name": "selector",
      "type": "string",
      "description": "The selector string."
    }
  ],
  "returns": [
    {
      "name": "nodeId",
      "$ref": "NodeId",
      "description": "Query selector result."
    }
  ],
  "description": "Executes `querySelector` on a given node."
}