Options to NOT use eval executing JSON string

Question

I want to see which options do I have to execute a string whichs looks for a value inside a JSON without using eval().

My JSON looks like this:

var caso = {
    "_id": "C1M3bqsB92i5SPDu",
    "type": "bpm",
    "bpm": {
        "_data": {
            "_id_bpm": "bpm_solicitud_viaticos"
        },
        "milestones": {
            "solicitud": {
                "toma_de_datos": {
                    "nombre": "RAUL MEDINA",
                    "clave": "123",
                    "departamento": "Finanzas",
                    "cantidad": "456"
                }
            }
        }
    }
}

Now, I'v a string with the value:

var step = "caso.bpm.milestones.solicitud.toma_de_datos.nombre";

I'm getting the value that I want from that JSON with this:

var thevalue = eval(step);

Which are my options instead of eval()? Both efficient and easy to implement?

Thanks a lot for your help!

Try a get from path function see [Javascript: Get deep value from object by passing path to it as string](http://stackoverflow.com/questions/8817394/javascript-get-deep-value-from-object-by-passing-path-to-it-as-string) or [What is the best to select a javascript object property at any depth?](http://codereview.stackexchange.com/questions/39979/what-is-the-best-to-select-a-javascript-object-property-at-any-depth) — megawac, Feb 11 '14 at 19:26
@Brad Your comment would actually be helpful if you posted a link explaining the difference. For all we know, the OP completely understands the difference and is simply showing an example of parsed JSON into an object literal that they are working with. — Ian, Feb 11 '14 at 19:34
@Ian You're right... that's why I added my comment. Either Laerion will know what I'm talking about and explain, or will show where the confusion is, so I can provide a targeted explanation. — Brad, Feb 11 '14 at 20:39

score 0 · Answer 1 · answered Feb 11 '14 at 19:27

0

If the string is always in that format, you could split it and iterate over it

var pieces = step.split('.');
var parent = window;

while(parent && pieces.length) {
    parent = parent[pieces.shift()];
}

if(parent && pieces.length === 0) {
    // parent is now the value
}

here is a fiddle: http://jsfiddle.net/9ZjEt/

answered Feb 11 '14 at 19:27

Matt Greer

60,826
17
123
123

There may be no window scope; there also may be no this :( – Dexygen Feb 11 '14 at 19:55
I'd reasonably expect the OP to figure that out. SO is to help move people in the right direction, not hold their hand. – Matt Greer Feb 11 '14 at 21:38

score 0 · Accepted Answer · answered Feb 11 '14 at 20:26

0

var pieces = step.split('.'),
    result;

pieces.shift(); //discards superfluous "caso"
result = caso[pieces.shift()];

while (pieces.length >= 1) {
    result = result[pieces.shift()];
}

answered Feb 11 '14 at 20:26

Dexygen

12,287
13
80
147

Options to NOT use eval executing JSON string

2 Answers2