[SOLVED] Access values from list page with Javascript

Hello,

I have a custom button in 'LIST PAGE'

$value = '<a class="custom_button btn btn-primary">CUSTOM BUTTON</a>';

how can I get its values using javascript on 'Javascript onload Event' ?

something like this:

$(".custom_button").on("click", function() {		
  alert(id); // ID or other DB values associated at this specific row
});	

thanks!