OverviewOfficial Website

Leaflet js is an open-source JavaScript library for mobile-friendly interactive maps.

CSS
<!-- leaflet Css -->
<link href="assets/libs/leaflet/leaflet.css" rel="stylesheet" type="text/css" />
Javascript
<!-- leaflet plugin -->
<script src="assets/libs/leaflet/leaflet.js"></script>
Initjs (Custom js)
<!-- leaflet map.init -->
<script src="assets/js/pages/leaflet-us-states.js"></script>
<script src="assets/js/pages/leaflet-map.init.js"></script>
Examples:
Title Javascript
Basic Example 
var mymap = L.map('leaflet-map').setView([51.505, -0.09], 13);
L.tileLayer('https://api.mapbox.com/styles/v1/{id}/
tiles/{z}/{x}/{y}?access_token=pk.eyJ1IjoibWFwYm94IiwiYSI6ImNpejY4NXVycTA2emYycXBndHRqcmZ3N3gifQ.
rJcFIG214AriISLbB6B5aw', {
maxZoom: 18,
attribution: 'Map data © OpenStreetMap contributors, ' +
'CC-BY-SA, ' +
'Imagery © Mapbox',
id: 'mapbox/streets-v11',
tileSize: 512,
zoomOffset: -1
}).addTo(mymap);
Markers, Circles and Polygons 
var markermap = L.map('leaflet-map-marker').setView([51.505, -0.09], 13);

L.tileLayer('https://api.mapbox.com/styles/v1/{id}/tiles/{z}/{x}/{y}?access_token=pk.
eyJ1IjoibWFwYm94IiwiYSI6ImNpejY4NXVycTA2emYycXBndHRqcmZ3N3gifQ.
rJcFIG214AriISLbB6B5aw', {
maxZoom: 18,
attribution: 'Map data © OpenStreetMap contributors, ' +
'CC-BY-SA, ' +
'Imagery © Mapbox',
id: 'mapbox/streets-v11',
tileSize: 512,
zoomOffset: -1
}).addTo(markermap);

L.marker([51.5, -0.09]).addTo(markermap);

L.circle([51.508, -0.11], {
color: '#0ab39c',
fillColor: '#0ab39c',
fillOpacity: 0.5,
radius: 500
}).addTo(markermap);

L.polygon([
[51.509, -0.08],
[51.503, -0.06],
[51.51, -0.047]
],{
color: '#405189',
fillColor: '#405189',
}).addTo(markermap);
Working with Popups 
var popupmap = L.map('leaflet-map-popup').setView([51.505, -0.09], 13);
L.tileLayer('https://api.mapbox.com/styles/v1/{id}/tiles/{z}/{x}/{y}?access_token=pk.
eyJ1IjoibWFwYm94IiwiYSI6ImNpejY4NXVycTA2emYycXBndHRqcmZ3N3gifQ.rJcFIG214AriISLbB6B5aw', {
maxZoom: 18,
attribution: 'Map data © OpenStreetMap contributors, ' +
'CC-BY-SA, ' +
'Imagery © Mapbox',
id: 'mapbox/streets-v11',
tileSize: 512,
zoomOffset: -1
}).addTo(popupmap);

L.marker([51.5, -0.09]).addTo(popupmap)
.bindPopup("Hello world!
I am a popup.").openPopup();

L.circle([51.508, -0.11], 500, {
color: '#f06548',
fillColor: '#f06548',
fillOpacity: 0.5
}).addTo(popupmap).bindPopup("I am a circle.");

L.polygon([
[51.509, -0.08],
[51.503, -0.06],
[51.51, -0.047]
],{
color: '#405189',
fillColor: '#405189',
}).addTo(popupmap).bindPopup("I am a polygon.");

var popup = L.popup();
Markers with Custom Icons 
var customiconsmap = L.map('leaflet-map-custom-icons').setView([51.5, -0.09], 13);

L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
attribution: '© 
OpenStreetMap contributors'
}).addTo(customiconsmap);

var LeafIcon = L.Icon.extend({
options: {
iconSize:     [45, 45],
iconAnchor:   [22, 94],
popupAnchor:  [-3, -76]
}
});

var greenIcon = new LeafIcon({iconUrl: 'assets/images/logo-sm.png'});

L.marker([51.5, -0.09], {icon: greenIcon}).addTo(customiconsmap);
Interactive Choropleth Map 
var interactivemap = L.map('leaflet-map-interactive-map').setView([37.8, -96], 4);

L.tileLayer('https://api.mapbox.com/styles/v1/{id}/tiles/{z}/{x}/{y}?access_token=pk.
eyJ1IjoibWFwYm94IiwiYSI6ImNpejY4NXVycTA2emYycXBndHRqcmZ3N3gifQ.rJcFIG214AriISLbB6B5aw', {
maxZoom: 18,
attribution: 'Map data © OpenStreetMap contributors, ' +
'CC-BY-SA, ' +
'Imagery © Mapbox',
id: 'mapbox/light-v9',
tileSize: 512,
zoomOffset: -1
}).addTo(interactivemap);

// get color depending on population density value
function getColor(d) {
return d > 1000 ? '#405189' :
d > 500  ? '#516194' :
d > 200  ? '#63719E' :
d > 100  ? '#7480A9' :
d > 50   ? '#8590B4' :
d > 20   ? '#97A0BF' :
d > 10   ? '#A8B0C9' :
        '#A8B0C9';
}

function style(feature) {
return {
weight: 2,
opacity: 1,
color: 'white',
dashArray: '3',
fillOpacity: 0.7,
fillColor: getColor(feature.properties.density)
};
}

var geojson = L.geoJson(statesData, {
style: style,
}).addTo(interactivemap);
Layer Groups and Layers Control 
var cities = L.layerGroup();

L.marker([39.61, -105.02]).bindPopup('This is Littleton, CO.').addTo(cities),
L.marker([39.74, -104.99]).bindPopup('This is Denver, CO.').addTo(cities),
L.marker([39.73, -104.8]).bindPopup('This is Aurora, CO.').addTo(cities),
L.marker([39.77, -105.23]).bindPopup('This is Golden, CO.').addTo(cities);


var mbAttr = 'Map data © OpenStreetMap 
contributors, ' +
'CC-BY-SA, ' +
'Imagery © Mapbox',
mbUrl = 'https://api.mapbox.com/styles/v1/{id}/tiles/{z}/{x}/{y}?access_token=pk.
eyJ1IjoibWFwYm94IiwiYSI6ImNpejY4NXVycTA2emYycXBndHRqcmZ3N3gifQ.rJcFIG214AriISLbB6B5aw';

var grayscale   = L.tileLayer(mbUrl, {id: 'mapbox/light-v9', tileSize: 512, 
zoomOffset: -1, attribution: mbAttr}),
streets  = L.tileLayer(mbUrl, {id: 'mapbox/streets-v11', tileSize: 512,
zoomOffset: -1, attribution: mbAttr});

var layergroupcontrolmap = L.map('leaflet-map-group-control', {
center: [39.73, -104.99],
zoom: 10,
layers: [streets, cities]
});

var baseLayers = {
"Grayscale": grayscale,
"Streets": streets
};

var overlays = {
"Cities": cities
};

L.control.layers(baseLayers, overlays).addTo(layergroupcontrolmap);
© Skote.