Why is my jQuery AJAX request sending data as plain text instead of JSON?

Sending JSON Data Effectively with jQuery

In web development, it's often crucial to transmit data efficiently between the client-side and the server. jQuery, a popular JavaScript library, offers convenient methods for handling such data exchange. One common task is sending data in JSON format to the server using jQuery.

However, sometimes developers encounter an issue where data is not transmitted in the desired JSON format but as plain text. To understand why this occurs, let's examine a code snippet:

var arr = {City:'Moscow', Age:25};
$.ajax(
   {
        url: "Ajax.ashx",
        type: "POST",
        data: arr,
        dataType: 'json',
        async: false,
        success: function(msg) {
            alert(msg);
        }
    }
);

This code attempts to send the data in the arr object to the Ajax.ashx server using the $.ajax method. However, the issue arises because the code does not specify the request content type or correctly construct the JSON request.

To rectify this, the JSON.stringify method should be used to convert the JavaScript object into a native JSON string:

var arr = { City: 'Moscow', Age: 25 };
$.ajax({
    url: 'Ajax.ashx',
    type: 'POST',
    data: JSON.stringify(arr),
    contentType: 'application/json; charset=utf-8',
    dataType: 'json',
    async: false,
    success: function(msg) {
        alert(msg);
    }
});

Key Points to Note:

• contentType: Specifies the request content type, indicating to the server that a JSON request is being sent.
• dataType: Indicates the expected response type from the server.
• JSON.stringify: Converts the JavaScript object into a JSON string.

Additional Considerations:

• The arr object is actually a JavaScript object, not an array. Arrays should be denoted with [].
• Be mindful of the server's response and verify that its Content-Type header correctly reflects a JSON response. Otherwise, jQuery will try to parse the response as a JSON regardless of its actual format.

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