`new Function` for json reference

Question

I have JSON with references to other parts in that JSON file.

// the function I would like to be reviewed
function referenceToObject(json, reference){
 return (new Function(
 'json', 'return json' + reference
 ))(json);
}
// json
var example = {
 "target": "['first']['second']",
 "first": {
 second: 'hi'
 }
};
// execution
console.log(referenceToObject(example, example.target));

That function basically executes like this:

return json['one']['two'];

Is there a better way to extract the JSON reference? I'm able to change every bit of this code, as well as the JSON because we are reworking the front- and the backend. So, if you have ideas to improve the JSON instead of the Javascript that would also be great.

• Joseph: Any reason why target is formatted in that way?
• Randy: @DavidFoerster @josephthedreamer I can change the Target, is it best to use reduce there to get the location returned (just learned that function) or should I use a different approach?

Answer 1

Assuming that you control over the value of the target attribute, I suggest to store the reference chain as a list of attribute names. Then you can easily resolve the reference without having to resort to eval-like meta-programming. A reduction would be ideal like you mentioned.

function referenceToObject(json, target)
{
	if (target === undefined)
		target = json.target;
	return target.reduce(referenceToObject.reductor, json);
}
referenceToObject.reductor = function(obj, attrib)
{
	return obj[attrib];
};
var example = {
	"target": ['first', 'second'],
	"first": {
		second: 'hi'
	}
};
console.log(referenceToObject(example));