angular - 从嵌套数组 Ionic3 未定义的 firebase 中删除项目 commig

Question

这是我在过滤来自 firebase 的数据后得到的结果，我想从对象中删除 1 次未定义的消息，只想显示未定义的消息，

    1:{name: "ESilva", 
    messages: undefined}
    2:
   {name:"teste chat",
    messages:
    -LCDFwauPWy-q_69PvS0:{date: "2018/5/11", haveConsultant: true, hour: "09:14", message: "Oi", user: "teste chat"}

// 我的 ionic 代码

    getUsersChat() {

      let clientsKeys: Array < any > ;

      let i = 0;
      console.log('obtain clients');
      this.mySegService.getClients().take(1).subscribe(res => {
        // console.log(res);
        clientsKeys = Object.keys(res);
        this.totalNumberClients += clientsKeys.length;
        clientsKeys.forEach(clientKey => {
          if (i < 99) {
            this.clientsShortList.push({
              name: res[clientKey]['name'],
              messages: res[clientKey]['messages']
            });
          }
          i += 1;
        });
      console.log(this.clientsShortList);  
    });

   }

Answer 1

您可以在代码中添加一个 if 检查

getUsersChat() {

  let clientsKeys: Array < any > ;

  let i = 0;
  console.log('obtain clients');
  this.mySegService.getClients().take(1).subscribe(res => {
    // console.log(res);
    clientsKeys = Object.keys(res);
    this.totalNumberClients += clientsKeys.length;
    clientsKeys.forEach(clientKey => {
      if (i < 99 && res[clientKey]['messages'] != undefined) {
        this.clientsShortList.push({
          name: res[clientKey]['name'],
          messages: res[clientKey]['messages']
        });
      }
      i += 1;
    });
  console.log(this.clientsShortList);  
});

}