How can I create an object mapping from an array of strings?

June 9, 2022

i am stumbling onto something that should be easy, yet i can’t seem to be able to do it.

i have an array of string, and i want to map over it to create an object like so :

const monthesList = ['january', 'february', 'march', 'april', 'may']

const myState = monthesList.map(month => (
    month: {selected: true, year: 2022}
    )
  )

what i want is to get the following object :

myState ={
  january:{ 
    selected: false,
    year: 2022
  },
  february:{ 
    selected: false,
    year: 2022
  },
  march:{ 
    selected: false,
    year: 2022
  },
  april:{ 
    selected: false,
    year: 2022
  },
  may:{ 
    selected: false,
    year: 2022
  },
}

Edit:
i just found the way :

const myState = monthesList.map(month => (
    {[month] : {
      selected: false,
      year: 2022
    }}
    )
  )

just need to make an object out of it, shouldn’t be too hard

>Solution :

The .map() method returns an array, but the output that you’re after is an object. You need something that can convert an array of key-value pairs (ie: [key, value]) to an object. For this, we have the Object.fromEntries() method that takes an array of key-value pairs, and from it, constructs an object like so:

const monthesList = ['january', 'february', 'march', 'april', 'may'];

const myState = Object.fromEntries(monthesList.map(month => [
  month, {selected: true, year: 2022}
]));
console.log(myState);