How to add only one marker in leaflet map

Question

I am adding marker on map on user click.
Problem is that I want only one marker but now whenever I click on map new marker is added.
I am trying to remove it but nothing happens:

var marker;
    map.on('click', function (e) {
        map.removeLayer(marker)

        marker = new L.Marker(e.latlng, { draggable: true });
        marker.bindPopup("<strong>" + e.latlng + "</strong>").addTo(map);

        marker.on('dragend', markerDrag);
    });

Answer 1

Instead of using .on to capture and handle the event, you could use .once. That way the event will be only captured once and the handler will unbind itself after that.

map.on('click', function () {
    console.log('I fire every click');
});

map.once('click', function () {
    console.log('I fire only once');
});

If you're ever need to unbind a handler yourself you can use .off. Check the reference for event methods: http://leafletjs.com/reference.html#events

As to why your code above isn't working, on first click you're trying remove the marker: map.removeLayer(marker), but the variable marker doesn't contain a L.Marker instance so the map is unable to remove it. You should check if it's defined first and only then remove it:

var marker;
map.on('click', function (e) {
    if (marker) { // check
        map.removeLayer(marker); // remove
    }
    marker = new L.Marker(e.latlng); // set
});

Here's a working example on Plunker: http://plnkr.co/edit/iEcivecU7HGajQqDWzVH?p=preview