How to detect if polygons overlap in leaflet - polygon

Question

I am using leaflet draw to create polygons.
My requirement is when a user draws a polygon ,it should not intersect/overlap with existing polygons.
I have used point in polygon leaflet to detect if point falls within the polygon and it is working,
but the problem is i am not able to detect if a line crosses another polygons.In this case points lie outside the existing polygons but overlapping exists.
Below attached image can give a better picture!

Answer 1

You can also probably use Turf.js. Turf is a new js GIS engine developed by the guys at Mapbox.
Here are few examples that may do the job:
Turf Intersects
Turf Overlaps

Answer 2

In leaflet.draw, you can pass options to individual draw handlers. One of them allowIntersection is a boolean type that "Determines if line segments can cross."
Your options would look something like this (excerpted from the leaflet.draw example config):
var options = {
position: 'topright',
draw: {
polygon: {
allowIntersection: false, // Restricts shapes to simple polygons
drawError: {
color: '#e1e100', // Color the shape will turn when intersects
message: '<strong>Oh snap!<strong> you can\'t draw that!' // Message that will show when intersect
},
shapeOptions: {
color: '#bada55'
}
},
},
edit: {
featureGroup: editableLayers, //REQUIRED!!
remove: false
}
};
var drawControl = new L.Control.Draw(options);
map.addControl(drawControl);

Answer 3

You can probably also use Terraformer Core, which is an open-source project done by the folks at ESRI. You would probably do something like this:
var polygon = new Terraformer.Primitive({
"type": "Polygon",
"coordinates": [ [ [ -101.46972656250001, 34.125447565116126 ],
[ -100.85449218750001, 33.760882000869195 ],
[ -101.09619140625, 33.19273094190692 ],
[ -102.12890625000001, 33.137551192346145],
[ -102.19482421875, 33.63291573870479 ],
[ -101.46972656250001, 34.125447565116126 ] ] ] });
var intersects = polygon.intersects({
"type": "Polygon",
"coordinates": [ [ [ -103.32539, 30.58608 ], [ -102.32083, 29.87894 ], [ -103.32539, 30.58608 ] ] ] });
// intersects is a bool.