API DOCUMENTATION

Once
Adds a listener that will be called only once to a specified event type occurring on features in a specified style layer.

map.once(type, layerId, listener)

Parameter 

[ example ]

map.once('click', function (e) {

    console.log('Click >>>>>>>',e)  //Map Click

})

  map.once('mouseover', 'fatosmarker', function (e) {

    if(e.originalEvent.toElement.id){  //marker mouseover

       console.log('Mouseover>>>>>>>',e)

    }

})