Object key error key.join is not a function

Question

What's wrong with this code? I'm trying to produce

james, 3245234545, [email protected]

class HelloWorldComponent extends React.Component {
    render() {

        const user = {
            name: "james",
            contact: "3245234545",
            email: "[email protected]",
            other: 'dsfsdfsdf'
        };

        return (      
            <div>{user &&
                <div>
                {Object.keys(user).map(key => {

                    if(key === 'name' || key==='contact' || key==='email'){
                        return user[key].join(', ')
                    }

                })}</div>
            }</div>
        )
    }
}

But I got error of

user[key].join is not a function

Here's my jsbin: http://jsbin.com/kuliwevoku/edit?js,console,output

Possible duplicate of Why is my join on a JavaScript array failing? — Shridhar R Kulkarni
– Shridhar R Kulkarni, Commented May 7, 2017 at 17:01

CD.. · Accepted Answer · 2017-05-07 17:15:27Z

3

You should join the map result:

Object.keys(user).map(key => {

                if(key === 'name' || key==='contact' || key==='email'){
                    return user[key]
                }

            }).join(', ')

You can filter the array too:

   Object.keys(user)
         .filter(key => ['name', 'contact', 'email'].includes(key))
         .map(key => user[key]).join(', ')

edited May 7, 2017 at 17:15

answered May 7, 2017 at 17:01

CD..

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4 Comments

Rick Hitchcock Over a year ago

Close, but this will return james, 3245234545, [email protected], . (Note the extra comma.)

Alan Jenshen Over a year ago

True. Didn't realized that.

Jonas Wilms Over a year ago

key !=="other" is slightly shorter... ;)

Rick Hitchcock Over a year ago

@Jonasw, that is shorter, but there may be keys besides other as well.

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