Zoom to fit all markers in Mapbox or Leaflet

How do I set view to see all markers on map in Mapbox or Leaflet? Like Google Maps API does with bounds?

E.g:

var latlngbounds = new google.maps.LatLngBounds();
for (var i = 0; i < latlng.length; i++) {
  latlngbounds.extend(latlng[i]);
}
map.fitBounds(latlngbounds);

var group = new L.featureGroup([marker1, marker2, marker3]);

map.fitBounds(group.getBounds());

See the documentation for more info.

The 'Answer' didn't work for me some reasons. So here is what I ended up doing:

////var group = new L.featureGroup(markerArray);//getting 'getBounds() not a function error.
////map.fitBounds(group.getBounds());
var bounds = L.latLngBounds(markerArray);
map.fitBounds(bounds);//works!

var markerArray = [];
markerArray.push(L.marker([51.505, -0.09]));
...
var group = L.featureGroup(markerArray).addTo(map);
map.fitBounds(group.getBounds());

Leaflet also has LatLngBounds that even has an extend function, just like google maps.

http://leafletjs.com/reference.html#latlngbounds

So you could simply use:

var latlngbounds = new L.latLngBounds();

The rest is exactly the same.

For Leaflet, I'm using

    map.setView(markersLayer.getBounds().getCenter());

Belatedly, I didn't see any answers using Mapbox, despite Mapbox has more functionality such as padding, animation, and max zoom.

const coordinates = [<coordiantes>...]

// Create a 'LngLatBounds' with the first coordinate.
const bounds = new mapboxgl.LngLatBounds(
  coordinates[0],
  coordinates[0]
);
 
// Extend the 'LngLatBounds' to include every coordinate in the bounds result.
for (const coord of coordinates) {
  bounds.extend(coord);
}

// Note there are other options such as easeing animation and maxZoom
map.fitBounds(bounds, {
  padding: 20
});

Demo

You also can locate all features inside a FeatureGroup or all the featureGroups, see how it works!

//Group1
m1=L.marker([7.11, -70.11]);
m2=L.marker([7.33, -70.33]);
m3=L.marker([7.55, -70.55]);
fg1=L.featureGroup([m1,m2,m3]);

//Group2
m4=L.marker([3.11, -75.11]);
m5=L.marker([3.33, -75.33]);
m6=L.marker([3.55, -75.55]);
fg2=L.featureGroup([m4,m5,m6]);

//BaseMap
baseLayer = L.tileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png');
var map = L.map('map', {
  center: [3, -70],
  zoom: 4,
  layers: [baseLayer, fg1, fg2]
});

//locate group 1
function LocateOne() {
    LocateAllFeatures(map, fg1);
}

function LocateAll() {
    LocateAllFeatures(map, [fg1,fg2]);
}

//Locate the features
function LocateAllFeatures(iobMap, iobFeatureGroup) {
		if(Array.isArray(iobFeatureGroup)){			
			var obBounds = L.latLngBounds();
			for (var i = 0; i < iobFeatureGroup.length; i++) {
				obBounds.extend(iobFeatureGroup[i].getBounds());
			}
			iobMap.fitBounds(obBounds);			
		} else {
			iobMap.fitBounds(iobFeatureGroup.getBounds());
		}
}

.mymap{
  height: 300px;
  width: 100%;
}

<script src="https://unpkg.com/[email protected]/dist/leaflet.js"></script>
<link href="https://unpkg.com/[email protected]/dist/leaflet.css" rel="stylesheet"/>

<div id="map" class="mymap"></div>
<button onclick="LocateOne()">locate group 1</button>
<button onclick="LocateAll()">locate All</button>

To fit to the visible markers only, I've this method.

fitMapBounds() {
    // Get all visible Markers
    const visibleMarkers = [];
    this.map.eachLayer(function (layer) {
        if (layer instanceof L.Marker) {
            visibleMarkers.push(layer);
        }
    });

    // Ensure there's at least one visible Marker
    if (visibleMarkers.length > 0) {

        // Create bounds from first Marker then extend it with the rest
        const markersBounds = L.latLngBounds([visibleMarkers[0].getLatLng()]);
        visibleMarkers.forEach((marker) => {
            markersBounds.extend(marker.getLatLng());
        });

        // Fit the map with the visible markers bounds
        this.map.flyToBounds(markersBounds, {
            padding: L.point(36, 36), animate: true,
        });
    }
}

You have an array of L.Marker:

let markers = [marker1, marker2, marker3]

let latlngs = markers.map(marker => marker.getLatLng())

let latlngBounds = L.latLngBounds(latlngs)

map.fitBounds(latlngBounds)
// OR with a smooth animation
// map.flyToBounds(latlngBounds)

//Create a point Layer (in this case a GeoJSON source)
let pointLayer = L.geoJSON(pointSource, {
    pointToLayerL pointToLayer,
    onEachFeature: onEachFeature
});
//Add the newly created layer to the mapObject
pointLayer.addTo(mapObject);

//Set a padding variable for the space around the bounds
let paddingCoef = (0.5);

//Call the fit bounds to adjust to the padded extent of points.
mapObject.fitBounds(pointLayer.getBounds().pad(paddingCoef));

The best way is to use the next code

var group = new L.featureGroup([marker1, marker2, marker3]);

map.fitBounds(group.getBounds());