How to get if a clicked area is within polygon in Google Maps

Interactive example on Playcode (opens new window)

Example

<!-- Source of JS implementation https://github.com/mattwilliamson/Google-Maps-Point-in-Polygon/blob/master/maps.google.polygon.containsLatLng.js -->
<template>
  <GMapMap
    ref="myMapRef"
    :click="true"
    @click="handleClick"
    :center="center"
    :zoom="10"
    map-type-id="terrain"
    style="width: 100vw; height: 20rem"
  >
    <GMapPolygon
      :options="{
          clickable: false
        }"
      :clickable="false"
      ref="mapPolygon"
      :paths="paths"
    />
  </GMapMap>
</template>

<script>
  import { ref, onMounted } from 'vue'
  import { setupContainsLatLng } from '../util/is-point-within-polygon.js'

  export default {
    data() {
      return {
        center: { lat: 25.774, lng: -80.19 },
        paths: [
          { lat: 25.774, lng: -80.19 },
          { lat: 18.466, lng: -66.118 },
          { lat: 32.321, lng: -64.757 },
        ],
      }
    },
    setup() {
      const myMapRef = ref()
      const mapPolygon = ref()

      function handleClick(event) {
        if (event.latLng?.lat) {
          mapPolygon.value.$polygonPromise.then((res) => {
            let isWithinPolygon = res.containsLatLng(event.latLng.lat(), event.latLng.lng())
            console.log({ isWithinPolygon })
          })
        }
      }

      onMounted(() => {
        myMapRef.value.$mapPromise.then(() => {
          setupContainsLatLng()
        })
      })

      return {
        myMapRef,
        mapPolygon,
        handleClick,
      }
    },
  }
</script>