gistfile1.txt

(function () {
  var submit = document.getElementById('submit')
  var input = document.getElementById('postcodeInput')
  var results = document.getElementById('results')
  var stores = [
    {
      name: 'The Good Wine Shop',
      lat: 51.4934165703256,
      lng: -0.249506824970951
    },
    {
      name: 'Albion Wine Shippers',
      lat: 51.522069316047,
      lng: -0.118444991313869
    },
    {
      name: 'New Zealand Cellar',
      lat: 51.4633202470804,
      lng: -0.111691966601662
    },
    {
      name: 'Passione Vino',
      lat: 51.5248490292883,
      lng: -0.0829685056508683
    }
  ]
  
  var storeGeojson = [
    {
      "type": "Feature",
      "geometry": {
        "type": "Point",
        "coordinates": [-0.249506824970951, 51.493416570325]
      },
      "properties": {
        "name": "The Good Wine Shop"
      }
    },
    {
      "type": "Feature",
      "geometry": {
        "type": "Point",
        "coordinates": [-0.118444991313869, 51.522069316047]
      },
      "properties": {
        "name": "Albion Wine Shippers"
      }
    },
    {
      "type": "Feature",
      "geometry": {
        "type": "Point",
        "coordinates": [-0.111691966601662, 51.4633202470804]
      },
      "properties": {
        "name": "New Zealand Cellar"
      }
    },
    {
      "type": "Feature",
      "geometry": {
        "type": "Point",
        "coordinates": [-0.0829685056508683, 51.5248490292883]
      },
      "properties": {
        "name": "Passione Vino"
      }
    }
  ]
  
  function arePointsNear(checkPoint, centerPoint, km) {
    var ky = 40000 / 360
    var kx = Math.cos(Math.PI * centerPoint.lat / 180.0) * ky
    var dx = Math.abs(centerPoint.lng - checkPoint.lng) * kx
    var dy = Math.abs(centerPoint.lat - checkPoint.lat) * ky

    return Math.sqrt(dx * dx + dy * dy) <= km
  }
  
  function arePointsWithinKm(from, to, km) {
      return turf.distance(from, to) <= km
  }

  submit.addEventListener('click', function (e) {
    var request = new XMLHttpRequest()
    var url = 'https://api.postcodes.io/postcodes/' + encodeURI(input.value)
    
    request.open('GET', url, true)
    
    request.onload = function() {
      if (this.status >= 200 && this.status < 400) {
        // Success!
        var data = JSON.parse(this.response)
        // var centerPoint = { lat: data.result.latitude, lng: data.result.longitude }
        var userPoint = turf.point([data.result.longitude, data.result.latitude]);
        // var filteredStores =  stores.filter(store => arePointsNear(store, centerPoint, 10))
        
        var filteredPoints =  storeGeojson.filter(storePoint => arePointsWithinKm(storePoint, userPoint, 5))
        
        if (filteredPoints.length <= 0) {
          results.innerHTML = 'No stores near you yet, but check back soon.'
          return
        }
        
        var nearestStore = turf.nearestPoint(userPoint, turf.featureCollection(filteredPoints));
        
        results.innerHTML = JSON.stringify(nearestStore)
 
      } else {
        // We reached our target server, but it returned an error
        var data = JSON.parse(this.response)
        results.innerHTML = data.error
      }
      console.log(this.response)
    }

    request.onerror = function() {
      results.innerHTML = 'Connection error'
    }
   
    request.send()
  })
})()