isValidJson.js

var isValidJSON = function isValidJSON(data) {
        if (String(data).length === 0) {
            return false;
        }
        try {
            var o = JSON.parse(data);     
            // if o checks for null, empty, or undefined.
            // typeof object and not instanceof array makes sure it's an object and not an array.
            // the error checker does the rest.
            if (o && typeof o === "object" && !(o instanceof Array)) {
                return true;
            }
        } catch (e) {
          return false;
        }
        return false;
};