How to encode an array as JSON?

Use JSON.stringify() (if you want to support older browsers, you have to include this file from Douglas Crockford):

$.ajax(
{
  "url": "some_script.php",
  "data": {json: JSON.stringify(gossIncome)},
  "success": function()
  {
    // Do something! 
  }
});

In a PHP script you could decode it with json_decode:

<?php

$json = isset($_GET['json']) ? $_GET['json'] : exit('No JSON passed!');

$array = json_decode($json);

if ( json_last_error() != JSON_ERROR_NONE )
  exit('JSON invalid!');

?>

try something like json_encode();

http://phpjs.org/functions/json_encode:457

This should do the job: http://www.openjs.com/scripts/data/json_encode.php

If you use jQuery or other JS Frameworks, look at there plugin repositories, normally they have a JSON class to de/encode arrays/objects...

The array is already technically in JSON, though to be passed via HTTP to a file, you'll want to serialize the data to maintain the name pair values as a string. Fortunately, jQuery has a built-in param() method. You could use it like this:

$.ajax({
    url: 'path/to/file.php',
    type: 'POST',
    data: $.param(grossIncome),
    success: function(msg) {
        console.log(msg); // or whatever
    }
});

Unfortunately, param() in only useful for arrays in the form of object maps... ie:

var grossIncome = {
    valueOne: "123",
    valueTwo: "321"
};