Cannot iterate through JavaScript object

Question

As a matter of exercise, I am trying to learn how to print the key and value of a JS object. I am having a hard time.

The following is a basic object I wrote and want to just print out the key : value

var obTest = {
    name: "John",
    WeddingDate: "10/18/2008",
    NumberKids: "2",
    Website: "www.samplewebsite.com
};


/* VERSION 1
for (var key in obTest) {
    // skip loop if the property is from prototype
    if (!obTest.hasOwnProperty(key)) continue;

    var obKey = obTest[key];
    for (var obProp in obKey) {
        // skip loop if the obProperty is from prototype
        if(!obKey.hasOwnProperty(obProp)) continue;

        // your code
        alert(obProp + " : " + obKey[obProp]);
    }
};
    // note: this prints each character as a key:value
*/

/* VERSION 2
for (var key in obTest) {
   if (obTest.hasOwnProperty(key)) {
      var obKey = obTest[key];
      for (var prop in obKey) {
         if (obKey.hasOwnProperty(prop)) {
            console.log(prop + " : " + obKey[prop]);
         }
      }
   }
};
    // note: this prints each character as a key:value
*/


// VERSION 3
Object.keys(obTest.forEach(function(key) {
    console.log(key, obTest[key]);
}));
    // note: this gives me a breakpoint and can't figure out why it does not work

As noted, VERSION 1 and VERSION 2 print the same output as follows:

0 : J
1 : o
2 : h
3 : n
0 : 1
1 : 0
2 : /
3 : 1
4 : 8
5 : /
6 : 2
7 : 0
8 : 0
9 : 8
0 : 2
0 : w
1 : w
2 : w
3 : .
4 : s
5 : a
6 : m
7 : p
8 : l
9 : e
10 : w
11 : e
12 : b
13 : s
14 : i
15 : t
16 : e
17 : .
18 : c
19 : o
20 : m

I get a breakpoint using Visual Studio Code for VERSION 3.

Please help me make an output like this:

    name : John
    WeddingDate : 10/18/2008
    NumberKids : 2
    Website : www.samplewebsite.com

I do not want to have numerical keys, especially ones that repeat themselves. Other articles I read don't seem to make any sense. Python seems pretty straightforward about iterating and printing object keys and values.

Thank you!

tarulen · Accepted Answer · 2016-11-01 14:24:35Z

3

You're using two nested loops, when one would be enough:

for (var key in obTest) {
  // skip loop if the property is from prototype
  if (!obTest.hasOwnProperty(key)) continue;
  //find the object corresponding to the current key
  var obKey = obTest[key];
  //output the key and the corresponding object  
  alert(key + " : " + obKey);
};

With your second loop, you enumerate all the pairs "keys : values" inside each value of your object. For a string "John", the pairs key:values are (0:"J", 1:"o", 2:"h", 3:"n")

For the version 3, you got the parenthesis wrong:

Object.keys(obTest) //close parenthesis of keys here
      .forEach(function(key) {
         console.log(key, obTest[key]);  
       });  //close only forEach here

edited Nov 1, 2016 at 14:24

answered Nov 1, 2016 at 13:58

tarulen

2,10010 silver badges15 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

baao · Accepted Answer · 2016-11-01 13:59:23Z

1

The third try is promising, but wrong implemented. To get the desired output, you can use

function objectString(obj) {
    var keys = Object.keys(obj);
    return keys.map(v => v + ": " + obj[v]).join("\n");
}

console.log(objectString(obTest));

answered Nov 1, 2016 at 13:59

baao

73.5k18 gold badges152 silver badges208 bronze badges

Comments

Tom M · Accepted Answer · 2016-11-01 14:08:52Z

1

Just use the example from the MDN Docs

for (var property in obTest) {
    if( obTest.hasOwnProperty( property ) ) {
       console.log(property + ": " + obTest[property])
    }
}

One of the problems is that you are missing a " behind the value of your "Website"-property.

http://codepen.io/anon/pen/ozKENQ

answered Nov 1, 2016 at 14:08

Tom M

2,9172 gold badges23 silver badges48 bronze badges

Comments

Amit Kumar Gupta · Accepted Answer · 2016-11-01 14:51:26Z

1

Use Object.keys() to get list of keys of an object. Then iterate to get their values.

var obTest = {
    name: "John",
    WeddingDate: "10/18/2008",
    NumberKids: "2",
    Website: "www.samplewebsite.com" };

Object.keys(obTest).forEach(function(key){        
    if (obTest.hasOwnProperty(key)){
        console.log(key + ":" + obTest[key]); 
    }
});

edited Nov 1, 2016 at 14:51

answered Nov 1, 2016 at 14:01

Amit Kumar Gupta

7,40912 gold badges69 silver badges95 bronze badges

3 Comments

host_255 Over a year ago

does forEach skip objects that have its own properties such as obTest.hasOwnProperty. If not, because I like the brevity of code, how do I add that into this?

Amit Kumar Gupta Over a year ago

forEach is just a function to iterate over an array.

Amit Kumar Gupta Over a year ago

I have updated the answer to print own property only.

Existe Deja · Accepted Answer · 2016-11-01 13:59:53Z

0

Object.keys(your_object) is your friend, it converts an object to an array. Check out the documentation here

answered Nov 1, 2016 at 13:59

Existe Deja

1,4093 gold badges17 silver badges38 bronze badges

Collectives™ on Stack Overflow

Cannot iterate through JavaScript object

5 Answers 5

Comments

Comments

Comments

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

Comments

Comments

Comments

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related