Question

36

Cannot read property 'length' of undefined react

rated 0 times [ 42] [ 6] / answers: 1 / hits: 33625 / 6 Years ago, mon, july 9, 2018, 12:00:00

TypeError: Cannot read property 'length' of undefined

That's what the compiler says when I run my react app. What I do need to do with this?

request = (start,end) => {

   if(this.state.teams.length < 1){

       axios.get(`${ URL }/teams`)

       .then( response => {

           this.setState({

               teams:response.data

           })

       })

   }



    axios.get(`${ URL }/articles?_start=${start}&_end=${end}`)

    .then( response => {

        this.setState({

            items:[...this.state.items,...response.data]

        })

    })

}

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janeth

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2 Years ago

answered 6 Years ago austonjuancarlosb · Accepted Answer

I would suggest to check first if the props is undefined or empty or even declared.

for example:-

    const card = props && props.cards && props.cards.length > 0 ?

        props.cards.map((card, i) => {

            return (

                <card >

            )

        }) : '';

And return your card.