You can add polylines in GMaps.js this way:
path = [[-12.044012922866312, -77.02470665341184], [-12.05449279282314, -77.03024273281858], [-12.055122327623378, -77.03039293652341], [-12.075917129727586, -77.02764635449216], [-12.07635776902266, -77.02792530422971], [-12.076819390363665, -77.02893381481931], [-12.088527520066453, -77.0241058385925], [-12.090814532191756, -77.02271108990476]]; map.drawPolyline({ path: path, strokeColor: '#131540', strokeOpacity: 0.6, strokeWeight: 6 });
The path of the polyline is defined by an array of array of two (latitude and longitude).