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

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: false, 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

CodePudding user response：

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: false, year: 2022}
]));
console.log(myState);

CodePudding user response：

You can use map to generate an array of arrays with the values in each internal array being the month name and object; then use Object.fromEntries to convert that into your desired object:

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

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

console.log(myState)

CodePudding user response：

map will only return an array. Your expected output is an object. There's no need to over-complicate things - use a simple loop instead.

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

const myState = {};

for (const month of list) {
  myState[month] = { selected: false, year: 2022 };
}

console.log(myState);