How do I use variable in JSON data in POST AJAX request?

Hey everyone, I am using POST AJAX request to send data to backend. I have one global variable names as 'lines' whose value is equal to 1 and it increments on button click. I want to send this value in POST request of AJAX. I have two values to send in JSON Form:

{
 "id":1,
 "line":4
}

How do I refer to 'lines' variable in lines parameter of data?

"{""key"":" & var & "}"

Although properly formatting JSON string with all those double and triple quotation marks is pretty difficult. Here is how I prefer to do it:

construct.net/en/forum/construct-3/how-do-i-8/ajax-data-syntax-error-167158

dop2000

Thank you, it worked.