json2.js is strict requiring all object keys be double-quoted. However, in Javascript syntax {"foo":"bar"}
is equivalent to {foo:"bar"}
.
I have a textarea that accepts JSON input from the user and would like to "ease" the restriction on double quoting the keys. I've looked at how json2.js validates a JSON string in four stages before it evals it. I was able to add a 5th stage to allow unquoted keys and would like to know if there are any security implications to this logic.
var data = '{name:"hello", age:"23"}';
// Make sure the incoming data is actual JSON
// Logic borrowed from http://json.org/json2.js
if ( /^[\],:{}\s]*$/.test(data.replace(/\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g, "@")
.replace(/"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g, "]")
.replace(/(?:^|:|,)(?:\s*\[)+/g, ":") // EDITED: allow key:[array] by replacing with safe char ":"
/** everything up to this point is json2.js **/
/** this is the 5th stage where it accepts unquoted keys **/
.replace(/\w+\s*\:/g, ":")) ) { // EDITED: allow any alphanumeric key
console.log( (new Function("return " + data))() );
}
else {
throw( "Invalid JSON: " + data );
}
!!! considering security risks -- do not eval blindly