Error ' missing : after property id' when using Jquery ajax function

Question

In the following code, I'm trying to send a key-value pair and I always get the error:
" missing: after property id "

$(".general").change(function () {
  fields = { $(this).attr('id') : "1" };
  $.ajax({
   type: "POST",
   url: "ajax/update_general.php",
   data: { fields: fields },
   dataType: "json",
   });
})

I've figured that what causes the problem is:

$(this).attr('id')

But I have no clue why. I've tried to first assign $(this).attr('id') to a variable, and put the variable in the ajax call, but that didn't help. How can I fix that?
Thank you!

Answer 1

It's a syntax error. You can't use the return value of a function call as a property name.

You can, however, use that return value in bracket notation after initializing the object:

  fields = {};
  fields[$(this).attr('id')] = '1';