Convert polygons to polylines in exported drawn Items from Draw Tools in IITC.

iitc-polygon-to-polyline.js

var drawnItems = [{"type":"polygon","latLngs":[{"lat":0,"lng":0},{"lat":0,"lng":60},{"lat":30,"lng":30}],"color":"#a24ac3"}];

drawnItems = drawnItems.map(o => o.type !== "polygon" ? o : { ...o, type: "polyline", latLngs: [...o.latLngs, o.latLngs[0]] });

copy(JSON.stringify(drawnItems));