ES6 map throws error on object array

You forgot to use ()

, write it like this:

const normalizeEventTypes = nextProps.events.space_events.map((obj, i) => 
     obj.id
)

      

        
        
        
      

    

Reason :

You are using obj and indexing both parameters in the callback function map

, so you need to use ()

to wrap parameters like:

a = b.map((i,j) => i)

      

        
        
        
      

    

These ()

are optional if we only want to use one parameter, for example:

a = b.map(i => i)

      

        
        
        
      

    

Various ways to use map

:

1. a.map(i => i + 1); //when index is not required

2.

 a.map(i => {  //when want to do some calculation
       //some calculation
       return //something;
 })

      

        
        
        
      

    

3. a.map((i,j) => i + j) //when want to use the index of item

Check out the working snippet:

let data = {
    "space_events": [{
            "id": 1,
            "name": "Anniversaries"
        },
        {
            "id": 2,
            "name": "Brand Rollout"
        }
    ]
}

let result = data.space_events.map((obj,i) => obj.name);

console.log('result', result);