How to enable "Same origin policy" by javascript/Jquery

from html
$('#btn_test').click(function () {
$.ajax(
{
type: "POST",
url: "http://localhost:5739/asmxservicestestservice.asmx/HelloWorld",
data: '{ "text": "Kartheek"}',
contentType: "application/json; charset=utf-8",
dataType: "json",
success: OnSuccess,
error: OnError

});

function OnSuccess(data, status) {
alert(data.d);

};
function OnError(msg) {
alert('error = ' + msg.d);
}

});


and my web service which is running on http://localhost:5739


[WebMethod ]
[ScriptMethod( ResponseFormat = ResponseFormat.Json)]
public string HelloWorld(string text)
{
return "Hello World" + text;
}