CCH via Vega-Lite

vega.json

{
  "$schema": "https://vega.github.io/schema/vega-lite/v3.json",
  "width": 360,
  "data": {
    "url": "https://code.gisce.net/empowering.js/cch.json",
    "name": "source",
    "format": {"type": "json"}
  },
  "selection": {
    "a": {
      "type": "single",
      "on": "click",
      "fields": ["_vgsid_"],
      "resolve": "global",
      "empty": "all"
    },

    "tooltip": {
      "type": "single",
      "nearest": true,
      "on": "mouseover",
      "encodings": [
        "x"
      ],
      "empty": "none"
    },

    "grid": {
      "type": "interval",
      "bind": "scales",
      "encodings": ["x"]
    }

  },
  "mark": {
    "type":"line",
    "point": true
  },
  "encoding": {
    "x": {"field": "date", "type": "temporal"},
    "y": {"field": "value", "type": "quantitative"},
    "color": {
      "condition": {"selection": "a", "value": "steelblue"},
      "value": "grey"
    }
  },
  "config": {}
}