Encountered an issue where property scrollToBottom is unable to be read of null upon returning to

Your system information:

Cordova CLI: 6.4.0

Ionic Framework Version: 2.0.0-rc.4

Ionic CLI Version: 2.1.14

Ionic App Lib Version: 2.1.7

Ionic App Scripts Version: 0.0.47

ios-deploy version: Not installed

ios-sim version: Not installed

OS: Windows 7

Node Version: v6.9.2

Xcode version: Not installed

Upon pushing to a Conversation-view, an error occurs. The client connects to a message server using socketIO to receive new messages and automatically scroll down to display the newest message. Initially, everything works fine, but when navigating back and returning to the page, an error is encountered.

Error Message:

Cannot read property scrollToBottom of null

connect() {
  this.socket.on("connect", () => {
      console.log("connected");  
      console.log("Listening on: "+"message_"+this.secretid);
      this.socket.emit('message', { type: "token", token: this.secretid });
      this.socket.on("message_"+this.secretid, (msg) => {
          let msg_data = JSON.parse(msg);
          msg_data.payload.writer_id = msg_data.payload.user;
          console.log(msg_data);
          this.chat.push(msg_data.payload);
          this.content.scrollToBottom(); <<--Error
      });
  });
}

Connect is called in ionViewDidLoad() {}, so this.content should be initialized.

I'm using Ionic 2.

Note: This error only occurs in Ionic Lab.

Answer №1

ionViewDidLoad lifecycle method is used for initializing the page and is only called once. Visit the documentation here

It's important to note that the view may not have finished loading yet.

In the provided code snippet, one solution could be to place the `scrollToBottom` call within the ionViewWillEnter method

Alternatively, you can also explore Angular's lifecycle hook ngOnChanges Here where you can monitor changes in the chat list

Answer №2

Give this a shot:

<section id="main-content">
 </section>

Answer №3

Make sure to place your this.content.scrollToBottom(0); within an if statement. Here's an example:

if( this.content._scroll ) {

this.content.scrollToBottom(0);

}

Give it a try and see if it works.

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