check if element exists in state array

Question

How could I access to the element in state array for example

this.state = {
    items: [1,5,22,6],
}

here I'm trying to set up a class if the id exists in items state

{this.props.data.map((row)=> (
 <ul>
  <li key={row.id} className={row.id === this.state.items ? 'complete' : 'pending'}" >{row.name}</li>
</ul>

))}

Chris · Accepted Answer · 2018-02-12 06:02:48Z

3

You can use the .includes() function for arrays:

{this.props.data.map((row)=> (
   <ul>
     <li key={row.id} className={this.state.items.includes(row.id) ? 'complete' : 'pending' }>{row.name}</li>
   </ul>
))}

Alternatively use .indexOf():

{this.props.data.map((row)=> (
   <ul>
     <li key={row.id} className={this.state.items.indexOf(row.id) !== -1 ? 'complete' : 'pending' }>{row.name}</li>
   </ul>
))}

answered Feb 12, 2018 at 6:02

Chris

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1 Comment

Jayce444 Over a year ago

Note that .includes() astonishingly isn't supported in IE.

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