将json对象保存到文件

I need to save a json object to a file. Therefore I'm using another PHP script which writes the data to a file. Data and filename are sent by an ajax POST request.

var results = $('results');
var filename = $('#filename').val();

$.ajax({
    url: 'jsonWriter.php',
    type: 'POST',
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    data: JSON.stringify([{data: data, filename: filename }]),
    success: function(data) {
        results.html(data);
    },
    error: function(jqXhr, textStatus, error) {
        results.html("<p class=\"error\">ERROR: " + textStatus + ", " + error + "</p>");
    }
});

When I monitor the request in Fiddler, it looks fine and the posted data is correct. However, somehow the error function is invoked. It outputs

ERROR: parsererror, SyntaxError: JSON.parse: unexpected non-whitespace character after JSON data

I copied the posted JSON data from Fiddler into different online parsers, which ensured it is valid.

Why is the error function invoked anyway?

It looks to me like you are expecting the server to return text content, since you are applying it with .html:

success: function(data) {
    results.html(data);
},

However, you are telling jQuery to expect JSON data:

dataType: "json",

jQuery is therefore attempting to parse your content returned from the server as JSON and failing. You need to change dataType to either text or html.