I find it surprising that no one mentions data as an object. For me it's the cleanest and easiest way to pass data:

$('form#foo').submit(function () {
    $.ajax({
        url: 'http://foo.bar/some-ajax-script',
        type: 'POST',
        dataType: 'json',
        data: {
            'foo': 'some-foo-value',
            'bar': $('#bar').val()
        }
    }).always(function (response) {
        console.log(response);
    });

    return false;
});

I find it surprising that no one mentions data as an object. For me it's the cleanest and easiest way to pass data:

$('form#foo').submit(function () {
    $.ajax({
        url: 'http://foo.bar/some-ajax-script',
        type: 'POST',
        dataType: 'json',
        data: {
            'foo': 'some-foo-value',
            'bar': $('#bar').val()
        }
    }).always(function (response) {
        console.log(response);
    });

    return false;
});

Then, in the backend:

// Example in PHP
$_POST['foo'] // some-foo-value
$_POST['bar'] // value in #bar

Just a friendly reminder that data can be an object, too:

$('form#foo').submit(function () {
    $.ajax({
        url: 'http://foo.bar/some-ajax-script',
        type: 'POST',
        dataType: 'json',
        data: {
            'foo': 'some-foo',
            'bar': 'some-bar'
        }
    }).always(function (data) {
        console.log(data);
    });

    return false;
});

I find it surprising that no one mentions data as an object. For me it's the cleanest and easiest way to pass data:

$('form#foo').submit(function () {
    $.ajax({
        url: 'http://foo.bar/some-ajax-script',
        type: 'POST',
        dataType: 'json',
        data: {
            'foo': 'some-foo-value',
            'bar': $('#bar').val()
        }
    }).always(function (response) {
        console.log(response);
    });

    return false;
});