JSTS

Read two point geometries A and B from WKT format

var reader = new jsts.io.WKTReader()
var a = reader.read('POINT (-20 0)')
var b = reader.read('POINT (20 0)')

Buffer A and B by 40 units

a = a.buffer(40)
b = b.buffer(40)

Intersection of A and B

var intersection = a.intersection(b)

Difference of A and B

var difference = a.difference(b)

Union of A and B

var union = a.union(b)

Symmetric difference of A and B

var symDifference = a.symDifference(b)