How can i loop through a nested object, using the for in loop and return each property string concatenated?

Question

For example i want to print the property values of first, middle, and last as concatenated strings.

The final output being: "John P. Doe"

var  person = {
    name: {
        first: 'John',
        middle: 'P',
        last: 'Doe'
    },
    age: 35,
    homeTown: 'Nashville, TN'
};

Why do you think you need a loop? Just concatenate the 3 properties. — Barmar, Nov 14 '16 at 21:51
Is there only going to be one person? You had mentioned a loop but your example doesn't exactly require the use of one. — Tyler Roper, Nov 14 '16 at 21:51
Related: [Access / process (nested) objects, arrays or JSON](http://stackoverflow.com/q/11922383/218196) — Felix Kling, Nov 14 '16 at 22:00

score 2 · Answer 1 · answered Nov 14 '16 at 21:52

2

You don't need a loop, just concatenate the properties.

var fullname = person.name.first + ' ' + person.name.middle + ' ' + person.name.last;

Using a for-in loop would be a bad idea, because objects aren't guaranteed to maintain their order. So you might end up with Doe John P. instead.

answered Nov 14 '16 at 21:52

Barmar

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Thanks Barmar !! Pretty new to programming. Didn't realize i could concatenate them. This was very useful ! – trenov Nov 21 '16 at 03:17

score 0 · Answer 2 · answered Nov 14 '16 at 21:56

0

these type of questions have been posted millions of times, do some research before asking.

anyway:

alert(person.name.first + ' ' + person.name.middle + ' ' + person.name.last);

answered Nov 14 '16 at 21:56

Paolo

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score 0 · Answer 3 · answered Nov 14 '16 at 21:58

you can use object.reduce for this

check this snippet

var person = {
  name: {
    first: 'John',
    middle: 'P',
    last: 'Doe'
  },
  age: 35,
  homeTown: 'Nashville, TN'
};


var nameObject = person.name;

var fullname = Object.keys(nameObject).reduce(function(previous, key) {
  return previous +" "+ nameObject[key];
}, "");

console.log(fullname);

Hope it helps

score 0 · Answer 4 · answered Nov 14 '16 at 22:03

You could use an array for the wanted property names (this keeps the order) and map the values and join it to a space separated string.

var  person = { name: { first: 'John', middle: 'P', last: 'Doe' }, age: 35, homeTown: 'Nashville, TN' };

console.log(['first', 'middle', 'last'].map(function (k) {
    return person.name[k];
}).join(' '));

score 0 · Answer 5 · answered Nov 14 '16 at 22:10

You can use destructuring assignment

var  person = {
    name: {
        first: 'John',
        middle: 'P',
        last: 'Doe'
    },
    age: 35,
    homeTown: 'Nashville, TN'
};

var {first, middle, last} = person.name;

var fullname = `${first} ${middle} ${last}`;

console.log(fullname);

score 0 · Answer 6 · answered Nov 14 '16 at 22:16

As Barmar's answer suggests, your example only needs a simple concatenation to give you your results.

However, in the more general case, you would want to iterate through each property of an object, and if the property is an object, iterate through that object as well.

For instance:

function iterateThroughAllProperties(obj) {
    Object.keys(obj).forEach(function(key, index) {
        if(typeof obj[key] !== null && typeof obj[key] === 'object') {
            iterateThroughAllProperties(obj[key]);
        }
        else {
            // Do something with the property.
            console.log(obj[key]);
        }
    });
}

Thanks Sesh! I was thinking along the lines of this solution before i realize how simple it was. I will most definitely study it. — trenov, Nov 21 '16 at 03:22

How can i loop through a nested object, using the for in loop and return each property string concatenated?

6 Answers6