OpenLayers绘制多边形解析GeoJSON报错：feature.getId is not a function

错误根源是writeFeatureObject方法的参数使用错误：该方法仅接受单个Feature对象，但你传入了包含Feature的数组[e.feature]，数组本身没有getId方法，因此触发报错。

修正后的代码：

const drawInteraction = new Draw({
  type:'Polygon',
  freehand:true
})
map.addInteraction(drawInteraction);
drawInteraction.on('drawend',function(e){
  let parser= new GeoJSON();
  // 移除数组包裹，直接传入单个feature对象
  let drawnFeatures = parser.writeFeatureObject(e.feature);
  console.log(drawnFeatures);
})      

如果需要批量处理多个Feature，改用writeFeaturesObject方法（参数为Feature数组）：

// 批量处理示例
let drawnFeatures = parser.writeFeaturesObject([featureA, featureB]);

内容的提问来源于stack exchange，提问作者panos9087