Leaflet.freedraw 插件画多边形官方标配写法：绘画操作函数：那么返回最新画的多边形坐标，咋整？画笔的功能和

官方标配写法：

import L from 'leaflet';
import FreeDraw from 'leaflet-freedraw';

const map = new L.Map(node);
const freeDraw = new FreeDraw();

map.addLayer(freeDraw);

绘画操作函数：

freeDraw.on('markers', event => {
    console.log(event.latLngs);    //   返回所有多边形坐标
});

那么返回最新画的多边形坐标，咋整？

var latestPolygon = eventData.latLngs.filter(function (latLngs) {
          const json = JSON.stringify(latLngs)
          const has = !~seenPolygons.indexOf(json)
          has && seenPolygons.push(json)
          return has
        })        //   latestPolygon 就是最新的这个多边形坐标

画笔的功能和一些默认值

Option	Default	Result
`mode`	`ALL`	Modifies the default mode.
`smoothFactor`	`0.3`	By how much to smooth the polygons.
`elbowDistance`	`10`	Factor to determine when to delete or when to append an edge.
`simplifyFactor`	`1.1`	By how much to simplify the polygon.
`mergePolygons`	`true`	Whether to attempt merging of polygons that intersect.
`concavePolygon`	`true`	Whether to apply the concaving algorithm to the polygons.
`maximumPolygons`	`Infinity`	Maximum number of polygons to be added to the map layer.
`recreateAfterEdit`	`false`	Whether to recreate the polygons subsequent to them being modified.
`notifyAfterEditExit`	`false`	Whether to defer `markers` event until after exiting `EDIT` mode.
`leaveModeAfterCreate`	`false`	Whether to exit `CREATE` mode after each polygon creation.
`strokeWidth`	`2`	Size of the stroke when drawing.

指定画笔有哪些功能，咋整？

// Allow create, edit and delete.
freeDraw.mode(CREATE | EDIT | DELETE);

// Allow everything except create.
freeDraw.mode(ALL ^ CREATE);

// Allow nothing.
freeDraw.mode(NONE);

各种方法函数：

Method	Yields	Result
`create`	`Array`	Creates a polygon by passing an array of `LatLng`s
`remove`	`void`	Removes a polygon that is yielded from `create`
`clear`	`void`	Clears all polygons from the current instance
`mode`	`Number`	Sets and retrieves the current `mode`.
`cancel`	`void`	Cancels the current create action – such as on escape.
`size`	`Number`	Yields the number of polygons on the map layer.
`all`	`Array`	Enumerate all of the current polygons for the current layer

备注：

单击多边形可以删掉