在3d场景的应用中经常需要将矢量数据保存为kml格式，下面来看一下如何实现
    首先安装 kml-geojson这个库

    1. npm i kml-geojson -S

    代码如下

    1. function saveGeoJSON2Kml(geojson: string, options: any): any {
    2.   const geojsonObject = clone(geojson, null, null)
    4.   const kml = toKml(geojsonObject, {
    5.     name: "Mars3D标绘数据",
    6.     documentName: "Mars3D标绘数据文件",
    7.     documentDescription: "标绘数据 by mars3d.cn",
    8.     simplestyle: true,
    9.     ...options
    10.   })
    11.   return kml
    12. }
    14. function clone(obj: any, removeKeys: any, level: any): any {
    15.   // 避免死循环，拷贝的层级最大深度
    16.   if (level == null) {
    17.     level = 9
    18.   }
    19.   if (removeKeys == null) {
    20.     removeKeys = ["_layer"]
    21.   }
    23.   if (obj === null || typeof obj !== "object") {
    24.     return obj
    25.   }
    27.   // Handle Date
    28.   if (isDate(obj)) {
    29.     const copy = new Date()
    30.     copy.setTime(obj.getTime())
    31.     return copy
    32.   }
    34.   // Handle Array
    35.   if (isArray(obj) && level >= 0) {
    36.     const copy = []
    37.     for (let i = 0, len = obj.length; i < len; i++) {
    38.       copy[i] = clone(obj[i], removeKeys, level - 1)
    39.     }
    40.     return copy
    41.   }
    43.   // Handle Object
    44.   if (typeof obj === "object" && level >= 0) {
    45.     try {
    46.       const copy: any = {}
    47.       for (const attr in obj) {
    48.         if (typeof attr === "function") {
    49.           continue
    50.         }
    51.         if (removeKeys.indexOf(attr) !== -1) {
    52.           continue
    53.         }
    55.         if (obj.hasOwnProperty(attr)) {
    56.           copy[attr] = clone(obj[attr], removeKeys, level - 1)
    57.         }
    58.       }
    59.       return copy
    60.     } catch (e) {
    61.       console.log(e)
    62.     }
    63.   }
    64.   return obj
    65. }
    66. function isArray(obj: any) {
    67.   if (typeof Array.isArray === "function") {
    68.     return Array.isArray(obj)
    69.   } else {
    70.     return Object.prototype.toString.call(obj) === "[object Array]"
    71.   }
    72. }
    73. function isDate(obj: any) {
    74.   return typeof obj === "object" && obj.constructor === Date
    75. }

    如果是vite项目，还需要将kml-geojson配置为预构建