I am using the other answer in a leaflet map to allow users to send me feature requests based on the clicked location in a map, which then opens a pre-filled google form with the lat long from that position. Those points are then shown on the map using sheetsee/tabletop. I added a map.hasLayer(my requests layer) so the user is not always seeing the popup when the map is clicked:
map.on('click', function(e) {
if (map.hasLayer(requests)) {
var requestform = e.latlng;
var formpopup = L.popup();
.setLatLng(requestform)
.setContent('<a href="' +href=" google form ' + e.latlng.lat +
'" target="_blank">Form</a>');
.openOn(map);
}
});