/
index.js
executable file
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/
index.js
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// [START maps_layer_data_quakes]
let map;
function initMap() {
map = new google.maps.Map(document.getElementById("map"), {
center: { lat: 20, lng: -160 },
zoom: 2,
styles: mapStyle,
});
map.data.setStyle(styleFeature);
// Get the earthquake data (JSONP format)
// This feed is a copy from the USGS feed, you can find the originals here:
// http://earthquake.usgs.gov/earthquakes/feed/v1.0/geojson.php
const script = document.createElement("script");
script.setAttribute(
"src",
"https://storage.googleapis.com/mapsdevsite/json/quakes.geo.json"
);
document.getElementsByTagName("head")[0].appendChild(script);
}
// Defines the callback function referenced in the jsonp file.
function eqfeed_callback(data) {
map.data.addGeoJson(data);
}
function styleFeature(feature) {
const low = [151, 83, 34]; // color of mag 1.0
const high = [5, 69, 54]; // color of mag 6.0 and above
const minMag = 1.0;
const maxMag = 6.0;
// fraction represents where the value sits between the min and max
const fraction =
(Math.min(feature.getProperty("mag"), maxMag) - minMag) / (maxMag - minMag);
const color = interpolateHsl(low, high, fraction);
return {
icon: {
path: google.maps.SymbolPath.CIRCLE,
strokeWeight: 0.5,
strokeColor: "#fff",
fillColor: color,
fillOpacity: 2 / feature.getProperty("mag"),
// while an exponent would technically be correct, quadratic looks nicer
scale: Math.pow(feature.getProperty("mag"), 2),
},
zIndex: Math.floor(feature.getProperty("mag")),
};
}
function interpolateHsl(lowHsl, highHsl, fraction) {
const color = [];
for (let i = 0; i < 3; i++) {
// Calculate color based on the fraction.
color.push((highHsl[i] - lowHsl[i]) * fraction + lowHsl[i]);
}
return "hsl(" + color[0] + "," + color[1] + "%," + color[2] + "%)";
}
const mapStyle = [
{
featureType: "all",
elementType: "all",
stylers: [{ visibility: "off" }],
},
{
featureType: "landscape",
elementType: "geometry",
stylers: [{ visibility: "on" }, { color: "#fcfcfc" }],
},
{
featureType: "water",
elementType: "labels",
stylers: [{ visibility: "off" }],
},
{
featureType: "water",
elementType: "geometry",
stylers: [{ visibility: "on" }, { hue: "#5f94ff" }, { lightness: 60 }],
},
];
// [END maps_layer_data_quakes]