Edit 5.18.2017: Raw CSS and Javascript via Leaflet Framework (recommended)
I was looking through the source code for the BoxZoom plugin and noticed their approach using Leaflet's built-in DOM mutators and wanted to promote it here...this is certainly the best practice.
Example jsfiddle
Somewhere in your CSS include a class like this..
.leaflet-container.crosshair-cursor-enabled {
cursor:crosshair;
}
When you want to enable crosshairs, do this in your JS..
// Assumes your Leaflet map variable is 'map'..
L.DomUtil.addClass(map._container,'crosshair-cursor-enabled');
Then, when you want to disable crosshairs, do this in your JS..
L.DomUtil.removeClass(map._container,'crosshair-cursor-enabled');
Original Answer: Map-level Crosshairs
@scud42 got me on the right path. You can use JQuery to change the Leaflet map cursor like this:
$('.leaflet-container').css('cursor','crosshair');
Then later, when you want to reset the map cursor, you can do this:
$('.leaflet-container').css('cursor','');
Edit 1.21.2016: Per-feature Crosshairs
You can also enable crosshairs for individual features supporting the className
option, such as a polygon, or feature vertices, etc.
Here's an example of a draggable vertice that will toggle pointer crosshairs (jsfiddle):
var svg_html_default = '<div style="margin:0px;padding:0px;height:8px;width:8px;border-style:solid;border-color:#FFFFFF;border-width:1px;background-color:#424242"</div>';
var default_icon = L.divIcon({
html: svg_html_default,
className: 'leaflet-mouse-marker',
iconAnchor: [5,5],
iconSize: [8,8]
});
var m = new L.marker([33.9731003, -80.9968865], {
icon: default_icon,
draggable: true,
opacity: 0.7
}).addTo( map );
m.on("mouseover",function(){$('.leaflet-mouse-marker').css('cursor','crosshair');});
m.on("mouseout",function(){$('.leaflet-mouse-marker').css('cursor','');});