You could just escape your string on the server when writing the value of the JSON field and unescape it when retrieving the value in the client browser, for instance.
The JavaScript implementation of all major browsers have the unescape command.
Example:
On the server:
response.write "{""field1"":""" & escape(RS_Temp("textField")) & """}"
In the browser:
document.getElementById("text1").value = unescape(jsonObject.field1)