Change zorder on hover

Show points on top when hovered over with the pointer

View this example in the online editor

Vega-Lite JSON Specification

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {
    "url": "https://cdn.jsdelivr.net/npm/vega-datasets@v1.29.0/data/cars.json"
  },
  "mark": {"type": "circle", "opacity": 1},
  "encoding": {
    "color": {
      "condition": {"param": "param_122", "value": "coral", "empty": false},
      "value": "grey"
    },
    "order": {
      "condition": {"param": "param_122", "value": 1, "empty": false},
      "value": 0
    },
    "size": {
      "condition": {"param": "param_122", "value": 400, "empty": false},
      "value": 100
    },
    "x": {"field": "Horsepower", "type": "quantitative"},
    "y": {"field": "Miles_per_Gallon", "type": "quantitative"}
  },
  "params": [
    {"name": "param_122", "select": {"type": "point", "on": "pointerover"}}
  ]
}