Javascript string instead of object expected

Question

var x = {};
x.a = {y:5};
x.b = {z:6};

for (prop in x) console.log(typeof prop); // returns "string". Why not "object"?

Shouldn't it return object? How do I get around this?

You should look at what prop is: jsfiddle.net/NnLrh/1

Jared Farrish
– Jared Farrish

2012-02-18 00:57:39 +00:00
Commented Feb 18, 2012 at 0:57 — Jared Farrish
– Jared Farrish, Commented Feb 18, 2012 at 0:57
How about reading some documentation?

Felix Kling
– Felix Kling

2012-02-18 00:58:20 +00:00
Commented Feb 18, 2012 at 0:58 — Felix Kling
– Felix Kling, Commented Feb 18, 2012 at 0:58

Ned Batchelder · Accepted Answer · 2012-02-18 00:58:01Z

1

If you output the prop's themselves, you'll see they are the keys: "a", "b".

answered Feb 18, 2012 at 0:58

Ned Batchelder

378k77 gold badges583 silver badges675 bronze badges

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

3 Comments

Ned Batchelder Over a year ago

The values that prop gets in the loop are the string "a", and then the string "b".

user1019031 Over a year ago

Right, but why does it get the string when "a" is an object?

Felix Kling Over a year ago

@user1019031: "a" is not an object, it is a string. x.a (or x["a"]) is an object. Have a look at the documentation I linked to in my comment.

dlchet · Accepted Answer · 2012-02-18 01:00:46Z

1

all of these responses are right, but perhaps you would see it better with a corrected example:

var x = {};
x.a = {y:5};
x.b = {z:6};

for (prop in x) console.log(typeof prop); // returns "string"
for (prop in x) console.log(prop); // returns "a", then "b"
for (prop in x) console.log(typeof x[prop]); // returns "object"
for (prop in x) console.log(x[prop]); // returns {y:5}, then {z:6}

answered Feb 18, 2012 at 1:00

dlchet

1,0637 silver badges13 bronze badges

1 Comment

user1019031 Over a year ago

Ah got it thank you! Just what I needed to get my head around it.

Ricardo Souza · Accepted Answer · 2012-02-18 00:58:14Z

0

Its returning the name of the properties.

answered Feb 18, 2012 at 0:58

Ricardo Souza

16.5k6 gold badges40 silver badges70 bronze badges

Comments

tlehman · Accepted Answer · 2012-02-18 01:00:46Z

0

Change your last line to

for (prop in x) console.log(typeof x[prop]);

The x[prop] part takes the property name, called prop (it is of type string) and returns the property x.prop, which for the case of a and b, will return object.

answered Feb 18, 2012 at 1:00

tlehman

5,1672 gold badges36 silver badges53 bronze badges

Collectives™ on Stack Overflow

Javascript string instead of object expected

4 Answers 4

3 Comments

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

3 Comments

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related