How to stop jQuery post page refresh - php

Question

I am getting data from an MySQL database through PHP. I am sending the and getting the data from PHP using jQuery. Here is the code.
$.POST("SubmitCode.php", $("#questionCodeForm").serialize(),'json').done(function(data) {});
Now the problem is that once I send this data the page refreshes. How can I stop the page refresh. If I delete 'json' then the page stops refreshing but the problem is that I want to get the json data without page refresh. How can I do this?
-------------------------------------------after edit-----------------------------------------------------------------------------
Here is the updated code
$(document).ready(function() {
initialization();
codeSubmission();
});
function initialization() {
$("#answerForm").hide();
}
function codeSubmission() {
$("#submitButton").click(function(e) {
e.preventDefault();
$.post("SubmitCode.php", $("#questionCodeForm").serialize()).done(function(data) {
var questionName = data.questionName,
options = data.options,
pollingStatus = data.pollingStatus,
codeExist = data.codeExist;
alert(data);
alert(data[1]);
alert(questionName);
alert(options);
if(codeExist == true) {
$("#questionTitle").text("questionName");
for(rowNum=1;rowNum<=5;rowNum++) {
$("#checkbox-"+rowNum).val("Answer1");
$("#checkbox"+rowNum+"label").text("Answer"+rowNum);
}
$("#answerForm").slideDown(500);
} else if(codeExist == false) {
alert("This quiz code is invalid");
}
},'json');
//return false;
});
//return false;
}
Now the problem is that the output of alert(questionName) is undefined. The data is passed as a string. How do I get the correct information in the correct variables?

Answer 1

Try this instead: (note the placement of the callback function, and lowercase .post method)
$.post("SubmitCode.php", $("#questionCodeForm").serialize(),function(data) {
//manipulate your data here
},'json');
Also make sure that whatever is triggering the post isn't an actual link and if it is, you need to stop the default action from occuring. For example:
Click here to submit
javascript:
$(a).click(function(e) {
e.preventDefault();
$.post("SubmitCode.php", $("#questionCodeForm").serialize(),function(data) {
//manipulate your data here
},'json');
});

Answer 2

You also have to parse the json on the client side. You can do this using
obj = jQuery.parseJSON(data);