Input two identical polygon will result in []

[zhanghaowx]

var polygonsIntersect = require('polygons-intersect'); 
var poly1 = [{x: 10, y: 10}, {x: 10, y: 30}, {x: 30, y: 30}, {x: 30, y: 10}];
console.log(polygonsIntersect(poly1, poly1));

Result will be [] but expected to be poly1