Options to NOT use eval executing JSON string [duplicate]

Question

This question already has answers here:

Javascript: Get deep value from object by passing path to it as string [duplicate] (5 answers)

Closed 8 years ago.

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!

Answer 1

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

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

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

Answer 2

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/