Accessing (Modifying) a class member inside an onload function

Question

I have stuck with a problem here,

I made a class named Ajax, in its constructor I've made a member named 'response' [this.response], Then I created the xhr object also a member.

Then I created a method named 'makeAjax(page, method)', which takes two arguments one for page and another for method of request.

Then, now when I used onload method, the problem starts. I'm want to access my this.response member inside the this.xhr.onload.

Im a newbie, so I'm bad with some bindings

Error:

Uncaught TypeError: Cannot assign to read only property 'response' of object '<#XMLHttpRequest>' at XMLHttpRequest.xhr.onload

https://code.sololearn.com/WBjlb1JFa0dJ/?ref=appError:

Uncaught TypeError: Cannot assign to read only property 'response' of object '<#XMLHttpRequest>' at XMLHttpRequest.xhr.onload

Answer 1

Hemath Kumar
As Calviղ explained, you can use a call back function to call another method after api.response has been assigned a value.

You can also attempt to load it after waiting a second or two.

Here are examples of both options. Just review the console output.

https://code.sololearn.com/WKOY3sSO1fkW/?ref=app

Answer 2

Oh it's all good. David Carroll
I am glad you have helped to clear the doubts.

Answer 3

You have to use callback onload, to get the data.

Answer 4

Hemath Kumar I only clarified one final part. Credit really should go to Calviղ.

I'm glad you have a better understanding. 😉👍

Answer 5

Hemath Kumar i cannot ignore your typo, you have serious error, xhr.send should be outside of onload.

Answer 6

You no longer can use this.xhr in the feedback onload, add bind function to the feedback, .bind(this.xhr)

Check out the code here
Add a status 200 checking too.

https://code.sololearn.com/WIobyxuF18Dt/?ref=app

Answer 7

Then you just .bind(this)
Check out the code again.

Answer 8

Hemath Kumar onload feedback output cannot get immediately due to network delay, this is why you need onload callback.

If you really need to get the this.reponse outside of onload fb after xhr.send, add some estimated delay before get the value.

Answer 9

Cleared my doubts!

Thanks for both

Calviղ

David Carroll

Answer 10

Some syntax errors on your code.

https://code.sololearn.com/WIobyxuF18Dt/?ref=app

Answer 11

Ignore them... That's just typo err.... I need the solution for binding

Answer 12

And I need something like

this.response = this.responseText;

Where, this.response comes from the constructor of AJAX Class.

How can I achieve that?

Answer 13

Okay cool... It's working now... Thanks...

But I tried another stuff,

I tried to access 'response' member by

api.response

After the call to api.makeAjax()

But it outputs nothing....

What is the problem or where I'm missing?

Answer 14

So what I have to do for that?

Can you pls help me to learn about it?