在HarmonyOS NEXT开发中Object is possibly 'undefined'. <ArkTSCheck>报错？

Question

在HarmonyOS NEXT开发中Object is possibly 'undefined'. <ArkTSCheck>报错？已经判断了变量是否为空，仍然会报错

Answer 1

参照以下写法：

if (this.port_pair_map != undefined && this.port_pair_map.get("123") != undefined) { 
  let arr: webview.WebMessagePort[] = this.port_pair_map.get("123") as webview.WebMessagePort[] 
    // arr[1].postMessageEvent("11111") 
  (this.port_pair_map.get("123") as webview.WebMessagePort[])[1].postMessageEvent("1111") 
}