data <- list(
  labels = c("Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"),
  datasets = list(
    list(name = "R", values = c(18, 40, 30, 35, 8, 52, 17, -4)),
    list(name = "Python", values = c(30, 50, -10, 15, 18, 32, 27, 14))
  )
)

tags$script(
  id = "data",
  type = "application/json",
  htmlwidgets:::toJSON(data)
)

let rData = document.getElementById('data')
rData.textContent

const data = {
    labels: ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"],
    datasets: [
      { name: "R", values: [18, 40, 30, 35, 8, 52, 17, -4] },
      { name: "Python", values: [30, 50, -10, 15, 18, 32, 27, 14] }
    ]
}

const chart = new frappe.Chart("#chart", {  // or a DOM element,
                                            // new Chart() in case of ES6 module with above usage
    title: "My Awesome Chart",
    data: data,
    type: 'line',
    height: 250,
    colors: ['#7cd6fd', '#743ee2']
})