How to escape a JSON string containing newline characters using JavaScript?

I have to form a JSON string in which a value is having new line character. This has to be escaped and then posted using AJAX call. Can any one suggest a way to escape the string with JavaScript. I am not using jQuery.

Take your JSON and .stringify() it. Then use the .replace() method and replace all occurrences of \n with \\n.

EDIT:

As far as I know of, there are no well-known JS libraries for escaping all special characters in a string. But, you could chain the .replace() method and replace all of the special characters like this:

var myJSONString = JSON.stringify(myJSON);
var myEscapedJSONString = myJSONString.replace(/\\n/g, "\\n")
                                      .replace(/\\'/g, "\\'")
                                      .replace(/\\"/g, '\\"')
                                      .replace(/\\&/g, "\\&")
                                      .replace(/\\r/g, "\\r")
                                      .replace(/\\t/g, "\\t")
                                      .replace(/\\b/g, "\\b")
                                      .replace(/\\f/g, "\\f");
// myEscapedJSONString is now ready to be POST'ed to the server. 

But that's pretty nasty, isn't it? Enter the beauty of functions, in that they allow you to break code into pieces and keep the main flow of your script clean, and free of 8 chained .replace() calls. So let's put that functionality into a function called, escapeSpecialChars(). Let's go ahead and attach it to the prototype chain of the String object, so we can call escapeSpecialChars() directly on String objects.

Like so:

String.prototype.escapeSpecialChars = function() {
    return this.replace(/\\n/g, "\\n")
               .replace(/\\'/g, "\\'")
               .replace(/\\"/g, '\\"')
               .replace(/\\&/g, "\\&")
               .replace(/\\r/g, "\\r")
               .replace(/\\t/g, "\\t")
               .replace(/\\b/g, "\\b")
               .replace(/\\f/g, "\\f");
};

Once we have defined that function, the main body of our code is as simple as this:

var myJSONString = JSON.stringify(myJSON);
var myEscapedJSONString = myJSONString.escapeSpecialChars();
// myEscapedJSONString is now ready to be POST'ed to the server