Can we combine regular for loops with for in

Question

I am curious but Google is not helping on this one...

We are looking for a tidy way of using an object key (it is an object containing functions) while also having clean access to the key names.

var obj={'key1':'val1','key2':'val2','key3':'val3'};

To get the desired key names in a loop we do: EDIT: this is wrong!

for(var i=0;i<obj.length;i++){
    console.log(Object.keys(obj)[i]);
    }

but would it be possible in this kind of loop?

for(var k in obj){
    //?
    }

I have seen combination loops before using &&. Is JavaScript able to do an elegant combination of both?

The closest I have got without disrupting the standard loop is:

var i=0;
for(var k in obj){
    console.log(Object.keys(obj)[i]);
    i++;
    }

but it is hardly elegant, not very innovative, it is more of a work around because 'i' is declared outside of the loop. Everything else we have tried errors.

Your first loop isn't even valid. `obj.length` is undefined because `obj`, as you've defined it, is a object and not an array. — Matt Burland, Jul 17 '14 at 13:09

score 5 · Accepted Answer · answered Jul 17 '14 at 13:07

5

If I understand your question, it's the simplest ever thing.

for(var k in obj){
    console.log(k);
}

answered Jul 17 '14 at 13:07

Denys Séguret

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Why the downvote ? Wasn't it what's asked ? – Denys Séguret Jul 17 '14 at 13:08
(I don't mean it should be upvoted either...) – Denys Séguret Jul 17 '14 at 13:10
Well it is a perfectly good answer. – Pointy Jul 17 '14 at 13:10
I know! some people are haters on here! Lol i must be REALLY tired. that is soooo easy its shocking! +1 – 8DK Jul 17 '14 at 13:10

score 1 · Answer 2 · answered Jul 17 '14 at 13:10

1

Alternatively:

Object.keys(obj).forEach(function(key) { console.log(key); });

answered Jul 17 '14 at 13:10

Pointy

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score 1 · Answer 3 · answered Jul 17 '14 at 13:10

1

If you need the keys:

for(var k in obj) {
  console.log(k)
}

If you need the values:

for(var k in obj) {
  console.log(obj[k])
}

answered Jul 17 '14 at 13:10

William Barbosa

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+1, I like the style of your answer – 8DK Jul 17 '14 at 13:11

score 0 · Answer 4 · answered Jul 17 '14 at 13:10

0

Are you trying to print out the keys and values?

for(var k in obj){
    console.log(k,obj[k]);
}

answered Jul 17 '14 at 13:10

Naren

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Can we combine regular for loops with for in

4 Answers4