Because you haven't specified neither request content type, nor correct JSON request. Here's the correct way to send a JSON request:
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);
}
});
Things to notice:
JSON.stringify method to convert a javascript object into a JSON string which is native and built-into modern browsers. If you want to support older browsers you might need to include json2.jscontentType property in order to indicate to the server the intent of sending a JSON requestdataType: 'json' property is used for the response type you expect from the server. jQuery is intelligent enough to guess it from the server Content-Type response header. So if you have a web server which respects more or less the HTTP protocol and responds with Content-Type: application/json to your request jQuery will automatically parse the response into a javascript object into the success callback so that you don't need to specify the dataType property.Things to be careful about:
arr is not an array. It is a javascript object with properties (City and Age). Arrays are denoted with [] in javascript. For example [{ City: 'Moscow', Age: 25 }, { City: 'Paris', Age: 30 }] is an array of 2 objects.