How to access the dynamic key in an array of objects

Question

I want to access the keys of the the objects in the array.

The example of object is:

var trackobj = {
        trackees: [{
            john: {
                "lat": "120000"
                , "long": "12345"
            }
            , harry: {
                "lat": "210000"
                , "long": "5433333"
            }
            , sid: {
                "lat": "420000"
                , "long": "21345"
            }
    }]
    }

I am using the function:

function searchTrackee() {
        for (var i = 0; i <= trackobj.trackees.length; i++) {
            console.log(trackobj.trackees[i]['key']);
        }
    }

The expected output I expect is "john" "harry" "sid".

Sidtharthan · Accepted Answer · 2017-07-29 07:23:14Z

4

I think the following should help you.

function searchTrackee() {
   trackobj.trackees.forEach(function(obj) {
      console.log(Object.keys(obj));
   });
}

EDIT 1:

I also agree with @MedAli. It is a good practice to use map and store it. Then print separately.

function searchTrackee() {
   var output = trackobj.trackees.map(function(obj){
       return Object.keys(obj);
   });
   console.log(output);
}

edited Jul 29, 2017 at 7:23

answered Jul 29, 2017 at 7:16

Sidtharthan

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Comments

Jay · Accepted Answer · 2017-07-29 07:15:02Z

3

you can do it with a simple for...in statement like this:

for (var i = 0; i <= trackobj.trackees.length; i++) {
    for(var key in trackobj.trackees[i]) {
        console.log(key);
    }
}

answered Jul 29, 2017 at 7:15

Jay

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Comments

Mohamed Ali JAMAOUI · Accepted Answer · 2017-07-29 07:26:47Z

You can do something like:

trackobj["trackees"].map(function(a){
 return Object.keys(a)
})

So you can update your code, as follows:

function searchTrackee() {
    var results = trackobj["trackees"].map(function(a){
     return Object.keys(a)
    })
    console.log(results)
}

The output is an array with the follows values:

["john","harry","sid"]

var trackobj = {
        trackees: [{
            john: {
                "lat": "120000"
                , "long": "12345"
            }
            , harry: {
                "lat": "210000"
                , "long": "5433333"
            }
            , sid: {
                "lat": "420000"
                , "long": "21345"
            }
    }]
    }
    
function searchTrackee() {
        var results = trackobj["trackees"].map(function(a){
         return Object.keys(a)
        })
        console.log(results)
}

searchTrackee();

Hassan Imam · Accepted Answer · 2017-07-29 07:30:34Z

0

You can also use Array#reduce to get all names.

var trackobj = {trackees: [{
            john: {
                "lat": "120000"
                , "long": "12345"
            }, harry: {
                "lat": "210000"
                , "long": "5433333"
            }, sid: {
                "lat": "420000"
                , "long": "21345"
            }}]
}

var names = trackobj['trackees'].reduce((names,obj) =>  names.concat(Object.keys(obj)),[]
);
console.log(names);

.as-console-wrapper { max-height: 100% !important; top: 0; }

answered Jul 29, 2017 at 7:30

Hassan Imam

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