订单簿深度

import { DepthChart } from '@tradecanvas/chart'

const depth = new DepthChart(el, {
  data: book,          // { bids: [{ price, size }], asks: [...] }
  midPriceLine: true,
  spreadLabel: true,
  theme: 'dark',
})
depth.update(nextBook)   // on every change of the book