How to get nested objects in javascript by an string as a bracket notation?

Question

I want a method in javascript that gets a string as its arguments and return a value from a nested object like as:

var obj = {
  place: {
    cuntry: 'Iran',
    city: 'Tehran',
    block: 68,
    info: {
     name :'Saeid',
      age: 22
    }
  }
};

function getValue(st) {
  // st: 'place[info][name]'
  return obj['place']['info']['name'] // or obj.place.info.name
}

The parameter st data format, can it be altered?

Rajaprabhu Aravindasamy
– Rajaprabhu Aravindasamy

2016-07-28 15:05:22 +00:00
Commented Jul 28, 2016 at 15:05 — Rajaprabhu Aravindasamy
– Rajaprabhu Aravindasamy, Commented Jul 28, 2016 at 15:05
No the data format of st can't be changed :)

SAlidadi
– SAlidadi

2016-07-28 15:08:06 +00:00
Commented Jul 28, 2016 at 15:08 — SAlidadi
– SAlidadi, Commented Jul 28, 2016 at 15:08
I can insert " after [ and before ] also

SAlidadi
– SAlidadi

2016-07-28 15:13:49 +00:00
Commented Jul 28, 2016 at 15:13 — SAlidadi
– SAlidadi, Commented Jul 28, 2016 at 15:13

VisioN · Accepted Answer · 2016-07-28 15:07:31Z

5

One possible solution for your use case:

function getValue(st, obj) {
    return st.replace(/\[([^\]]+)]/g, '.$1').split('.').reduce(function(o, p) { 
        return o[p];
    }, obj);
}

console.log( getValue('place[info][name]', obj) );  // "Saeid"
console.log( getValue('place.info.age', obj) );     // 22

answered Jul 28, 2016 at 15:07

VisioN

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2 Comments

Samuel Over a year ago

Hi, can you please take a look at stackoverflow.com/questions/64911518/… . :(

yasintuncel Over a year ago

what about setValue(st, obj, value) ?

footy · Accepted Answer · 2016-07-28 15:17:54Z

1

Can you get your input in the form of "['a']['b']['c']"?

function getValue(st) {
  // st: "['place']['info']['name']"
  return eval("obj"+st);
}

You can apply transformation to any strings and get the result.

EDIT:

DO NOT Use Eval directly in your code base. Its evil!

edited Jul 28, 2016 at 15:17

answered Jul 28, 2016 at 15:14

footy

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3 Comments

VisioN Over a year ago

eval will never be the best solution unfortunately.

footy Over a year ago

thats true but the question is the most unusual one I have seen

VisioN Over a year ago

I've seen such before and even answered one: stackoverflow.com/a/13719799/1249581. Funny but I even used that code in some projects at work.

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