Question

I have the following JSON: http://pastebin.com/Sh20StJY

^{SO removed the chars on my post, so look at the link for the real JSON}

which was generated using JSON.stringify and saved on Firefox prefs (pref.setCharPref(prefName, value);)

The problem is that when I save the value, Firefox does something that corrupts the JSON. If I try a JSON.parse retrieving the value from the config I get an error:

Error: JSON.parse: bad control character in string literal

If I try to validate the above JSON (which was retrieved from the settings) I get an error at line 20, the tokens value contains two invalid characters.

If I try a JSON.parse immediately after JSON.stringify the error doesn’t occur.

Do I have to set something to save in a different encoding? How can I fix it?

Answer 1

nsIPrefBranch.getCharPref() only works for ASCII data, your JSON data contains some non-ASCII characters however. You can store Unicode data in preferences, it is merely a little bit more complicated:

var str = Components.classes["@mozilla.org/supports-string;1"]
                    .createInstance(Components.interfaces.nsISupportsString);
str.data = value;
pref.setComplexValue(prefName, Components.interfaces.nsISupportsString, str);

And to read that preference:

var str = pref.getComplexValue(prefName, Components.interfaces.nsISupportsString);
var value = str.data;

For reference: Documentation