React-native array check if value exist

Question

How do check if ticketId already inserted into array?

This is the code:

state = { myState: [], status: 0, limit: 5 };

  selected(ticketId) {
  if (this.state.status < this.state.limit) { 
    this.state.myState.push({ id: ticketId }); //what ever i chose get inserted
    this.state.status++;
    this.setState({ status: this.state.status }); 
    //console.log('here', this.state.status);
  } else {
    console.log('3'); //check if condition meet
  }
 }

How do I create a condition checking myState array if the ticketId already insert and trigger an alert?

prabhatojha · Accepted Answer · 2017-09-26 06:31:15Z

3

As you are storing as an object {id:value}, better use "every" instead.

state = { myState: [], status: 0, limit: 5 };

selected(ticketId) {
   if (this.state.status < this.state.limit ) { 
      if(this.state.myState.every((item) => item.id !== ticketId)){
        this.state.myState.push({ id: ticketId }); //what ever i chose get inserted
        this.state.status++;
        this.setState({ status: this.state.status }); 
      //console.log('here', this.state.status);
     }
   } else {
   console.log('3'); //check if condition meet
   } 
}

answered Sep 26, 2017 at 6:31

prabhatojha

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Comments

Bhavan Patel · Accepted Answer · 2017-09-26 06:00:04Z

Hello you can use loadash Find it Here for this kind of problems its easy and very good looking! :)

Example:1

_.indexOf([1, 2, 1, 2], 2);
// => 1

Or You can Use

Example:2

var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.findIndex(users, function(o) { return o.user == 'barney'; });
// => 0

// The `_.matches` iteratee shorthand.
_.findIndex(users, { 'user': 'fred', 'active': false });
// => 1

// The `_.matchesProperty` iteratee shorthand.
_.findIndex(users, ['active', false]);
// => 0

// The `_.property` iteratee shorthand.
_.findIndex(users, 'active');
// => 2

In your code

_.findIndex(this.state.myState, { 'id': ticketId });
// It will return 0 if there is nothing 
// else will return no of index 
// where it ticketid is present 
// you can do alert on if its not 0

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