npm install flatten-offset

javascript
let offsetPolygon = polygon.offset(offset_value)
`
Instance of FlattenJS library is added as a property to the Offset class.
There is no need to install FlattenJS package separately.
Example:
`javascript
let Offset = require('flatten-offset');
let Flatten = Offset.Flatten;
let {segment, point, Polygon} = Flatten;
// Create polygon
let shapes = [
segment(point(200,100), point(200,300)),
segment(point(200,300), point(440,300)),
segment(point(440,300), point(300,200)),
segment(point(300,200), point(440,150)),
segment(point(440,150), point(500,150)),
segment(point(500,150), point(640,200)),
segment(point(640,200), point(500,300)),
segment(point(500,300), point(740,300)),
segment(point(740,300), point(740,100)),
segment(point(740,100), point(200,100))
];
let polygon = new Polygon();
polygon.addFace(shapes);
// Apply polygon offset
let offsetPolygon = polygon.offset(20);
``