How can I send data from a textbox.value to a collection?

Hi I’m adding value to a textbox using Javascript. so I have something like this:

$w('#mybox').value = "my string" ;

next I have a dataset to send the data from a bunch of input elements including ‘#mybox’ when a submit button is clicked.

My problem is: When I send the data to my collection in my database, all the data is received correctly from the input elements except the data from:

$w('#mybox').value = "my string" ;

What am I doing wrong? Am I using the right method? property?
I appreciate any suggestion, help.
Kind regards.

This is a very often asked question. If you set a value in code, you have to use setFieldValue() to get it into the dataset. wix-dataset - Velo API Reference - Wix.com

Hi Giri, thanks a lot this part of the documentation was really helpful!
Kind regards.