@data-ui/sparkline/esm/utils/findClosestDatum.js

React + d3 library for creating sparklines

import { bisector } from 'd3-array';
import localPoint from '@vx/event/build/localPoint';
export default function findClosestDatum(_ref) {
  var data = _ref.data,
      getX = _ref.getX,
      xScale = _ref.xScale,
      event = _ref.event,
      _ref$marginLeft = _ref.marginLeft,
      marginLeft = _ref$marginLeft === void 0 ? 0 : _ref$marginLeft;
  if (!event || !event.target || !event.target.ownerSVGElement) return {};
  var bisect = bisector(getX).right;
  var svgCoords = localPoint(event.target.ownerSVGElement, event);
  var x = svgCoords.x - marginLeft;
  var dataX = xScale.invert(x);
  var index = bisect(data, dataX, 1);
  var d0 = data[index - 1];
  var d1 = data[index];
  var d = !d0 || Math.abs(dataX - getX(d0)) > Math.abs(dataX - getX(d1)) ? d1 : d0;
  return {
    datum: d,
    index: d === d0 ? index - 1 : index
  };
}