To get JSON data using JavaScript for data stored as JSON string in the database you can use

for(var i = 0; i < modules.length; i++) {
    var moduleJSON = modules[i].json; // JSON string
    var parsedModule = JSON.parse(moduleJSON); // JSON Object
...

modules is the name for data objects here but it could of course be another denominator. Now, first you do a for loop to check if the length is larger than 0 for the JSOn string. If so you continue by loading the JSON string in a variable moduleJSON. Or.. another name.

Then you parse the JSON string and turn it into a JSON object you can then work with. In this case it would be called parsedModule. That is the object.