Javascript - Running a function that is stored in a JSON property

Question

I have a JSON object, like this:

var JSON = 
[
  {
    "cat_function":"(function(){console.log('ITS HAPPENING');})();"
  }
]

JSON[0].cat_function;

From my script, I need to load in the function and execute it. Simply calling JSON[0].cat_function doesn't work, which I kinda expected; what's the best way to get this to run?

To clarify, this JSON data is coming from a CSV and the function is obviously more complex than just a console.log. The function is stored as a string and there's not much that can be done about it.

Any ideas?

Answer 1

you could do

var functionCode = JSON[0].cat_function;

var value = eval( functionCode );

Anyway, I should warn you that eval is evil so if you can implement another way to import the code it will be better.

Answer 2

This is more a comment/pseudo-code because i currently don't use node.js often (so i could be wrong about it).

But what about doing it in a similar way how jsonp works in the browser:

The response you create (loaded data)

handleResponse({
    status : 200,  /* some statuscode like 200, 400 if required */
    data : {
         cat_function : function(){
                            console.log('ITS HAPPENING');
                        },
        some_data : 12345
    }
});

The function that handles the response (in your application code)

 function handleResponse( response ) {
    response.data.cat_function();
 }

The part where you load and execute it (in your application code)

 vm = require('vm');
 yourResponse = functionToLoadTheResponse();
 vm.runInThisContext(yourResponse);