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Mapbox: Zooming Out One Level After Using fitBounds Re-Centers Map

I am using Mapbox GL JS and created a dynamic store locator based on their store locator demo. I am using fitBounds to include all store markers on the initial display of the map.
The problem is, it zooms in too close and the map needs a bit of padding. So, I'm trying to back out the zoom one level. The problem is, when I get the zoom level and back out one, the map is recentered to the original center of the map.
I have included code below where I try to reset the center to the fitBounds center but it's not working. Any idea what I'm doing wrong?
var bounds = new mapboxgl.LngLatBounds();
$(markers).each(function() {
var features = $(this);
bounds.extend(features[0].geometry.coordinates);
});
map.fitBounds(bounds);
var mapLat = map.getBounds().getCenter().lat;
var mapLong = map.getBounds().getCenter().long;
map.setCenter = (mapLat, mapLong);
var mapZoom = map.getZoom();
newZoom = mapZoom - 1;
map.setZoom(newZoom);

If all you want to achieve is to add padding to the bounds, mapbox-gl provides an option for this in fitBounds:
map.fitBounds(bounds, {padding: 100}) // adds 100px padding to the bounds
Here is the documentation: https://www.mapbox.com/mapbox-gl-js/api#map#fitbounds

Automatically adjust map zoom to when marker added or deleted

I want to adjust map zoom at max where all markers can accommodate in it, I am able to add new markers and adjust zooming level with following code,
bounds.extend(markerPosition);
googleMap.fitBounds(bounds);
but I want this work in reverse too, like if I remove marker from map zooming level should be adjusted automatically.
Can we do it using Google "Bounds" API ?
Please help....

For overcoming this issues what I have done is, simply written a resetMapBounds() function as follows and called it everytime marker is added,edited or deleted and also adjusted zoom level as I required in it.
function resetMapBounds(){
var bounds = new google.maps.LatLngBounds();
for(var i=0;i<markers.length;i++){
bounds.extend(markers[i].position);
}
map.fitBounds(bounds);
if(map.getZoom()>18){
map.setZoom(18);
}
}

Prevent duplicating of map and keep dragging within world

Is there a way to make leaflet not repeat the world map and make the map stay within the world bounds when dragging? and also disable zoom out when the size of the world reaches the size of the window

To stop the tiles from repeating, use the noWrap option of L.TileLayer
If set to true, the tiles just won't load outside the world width (-180 to 180 longitude) instead of repeating.
http://leafletjs.com/reference.html#tilelayer-nowrap
If you want to stop panning beyond defined bounds, use the maxBounds option of L.Map or call the setMaxBounds method:
Restricts the view to the given geographical bounds, bouncing the user back when he tries to pan outside the view.
http://leafletjs.com/reference.html#map-maxbounds
http://leafletjs.com/reference.html#map-setmaxbounds
If you want to disable zoom beyond a certain level use L.Map's minZoom and maxZoom options. What you want to do is set a minimum zoom level and use that as initial zoom. What factor depends on your map's elementsize and your tilelayer's tilesize. Most tileproviders use 256px². At zoom 0 the world is 1 tile, at zoom 1, 2x2 tiles, at 3 it's 4x4 etc. So if your map's elements is 512px² your minZoom would be 1.
http://leafletjs.com/reference.html#map-minzoom
Here's a demonstration on Plunker: http://embed.plnkr.co/rP5NLQ/preview

By Setting minimum zoom level :
map._layersMinZoom=1 (which sets the minimum zoom level to 1)
OR
map.options.minZoom = 1;
Read more here

Leaflet JS - center and zoom on feature group

Code:
var map = L.map('map');
L.tileLayer('//{s}.tile.cloudmade.com/41339be4c5064686b781a5a00678de62/998/256/{z}/{x}/{y}.png',{minZoom:8, maxZoom:15}).addTo(map);
marker1 = L.marker([37.4185539, -122.0829068]).addTo(map);
marker1.bindPopup("Google Campus");
marker2 = L.marker([37.792359, -122.404686]).addTo(map);
marker2.bindPopup("Financial District");
var group = new L.featureGroup([marker1, marker2]);
map.fitBounds(group.getBounds());
The above code will center the map on the center of the markers, but does not set a zoom level so that the markers and only the markers are visible.
If I leave out the 'minZoom' attribute of the map object when adding the initial layer, the entire globe is visible. My desire is to have the map set a zoom and boundaries so that the markers are visible, and zoomed in. Any clues on how to accomplish this?
I thought that the fitBounds method would set a Zoom level, but for some reason in my situation it does not do so.

Your code is setting the map to a zoom level where both of the markers are visible at the highest possible zoom level. Because of the distance between the two markers and the way web mapping works, this is best fit using raster map tiles. Higher zoom levels will be zoomed in so much that you won't be able to see both markers.

How to listen for a layer zoom event in Polymaps?

I'm using Polymaps.js library for making maps.
It would be very useful to be able to observe zoom level changes on layers. I'm trying to keep a layer of points scaled by values in meters, so I need to recalculate the radii whenever the zoom level changes.

I'm using the on "move" function, which I think is triggered on zooms, too. There may be on on "zoom" function, too. I think that there is.
For example:
// whenever the map moves...
map.on("move", function() {
// get the current zoom
var z = map.zoom();
// show/hide parcels
parcels.visible(z >= 16);
});