Hi @shatilarefin
ACF provides some basic support for submitting data from the front end. You can read about it here:
http://www.advancedcustomfields.com/resources/tutorials/using-acf_form-to-create-a-new-post/
If you wish to code this manually, you can use the update_field function:
http://www.advancedcustomfields.com/resources/functions/update_field/
There is no JS function to get, or update a value. Only PHP functions are available.
Thanks
E