Mapping array into object keyed by array value

Question

I need to be able to remove object from object based on array values.

I have a base object:

   const obj = {
      one: {
        selected: undefined,
      }, 
      two: {
        selected: undefined,
      },
      three: {
        selected: undefined,
      }
    };

Example array is:

const arr = ['one', 'two'];

My attempt at doing this:

const mappedObj = arr.map(val => {
  if (obj[val]) {
    return ({
      [val]: {
        selected: true
      },
    });
  }

  return false;
})

I need it to be:

object: {
  one: {
    selected: true,
  },
  two: {
   selected: true,
  }
}

How is it determined that one.selected is true and two.selected is false as per your expected result? — charlietfl
– charlietfl, Commented Aug 9, 2018 at 12:54

Nina Scholz · Accepted Answer · 2018-08-09 12:57:17Z

1

You could map single objects and assign them to a single object with Object.assign and spread syntax ... for the array.

var object = { one: { selected: undefined, foo: 42 }, two: { selected: undefined }, three: { selected: undefined } },
    array = ['one', 'two'],
    result = Object.assign(
        ...array.map(k => ({ [k]: Object.assign({}, object[k], { selected: true }) }))
    );
  
console.log(result);

edited Aug 9, 2018 at 12:57

answered Aug 9, 2018 at 12:51

Nina Scholz

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2 Comments

hsz Over a year ago

selected is not set to true

hsz Over a year ago

I'd also suggest just in case: { ...obj[k], selected: true }

hsz · Accepted Answer · 2018-08-09 12:49:27Z

0

You can try with reduce on arr array:

const result = arr.reduce((acc, key) => {
  if (obj[key]) {
    acc[key] = { ...obj[key], selected: true };
  }
  return acc
}, {});

answered Aug 9, 2018 at 12:49

hsz

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Comments

Ankit Agarwal · Accepted Answer · 2018-08-09 12:49:36Z

0

You can use simple forEach() loop:

const obj = {
      one: {
        selected: undefined,
      }, 
      two: {
        selected: undefined,
      },
      three: {
        selected: undefined,
      }
    };

const arr = ['one', 'two'];
Object.keys(obj).forEach((key) => obj[key].selected = arr.includes(key));
console.log(obj);

answered Aug 9, 2018 at 12:49

Ankit Agarwal

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Comments

seduardo · Accepted Answer · 2018-08-09 13:02:30Z

0

You can use "reduce" instead of "map":

const obj = {
      one: {
        selected: undefined,
      }, 
      two: {
        selected: undefined,
      },
      three: {
        selected: undefined,
      }
    };
const arr = ['one', 'two'];
const mappedObj = arr.reduce((acm, val) => { 
    if (val in obj) { 
      acm[val] = { selected: true };
    }
    return acm;
  }, 
  {}
);

result:

{ one: { selected: true }, two: { selected: true } }

answered Aug 9, 2018 at 13:02

seduardo

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Comments

Mohammed Ashfaq · Accepted Answer · 2018-08-09 13:08:09Z

0

const obj = {
      one: {
        selected: undefined,
      }, 
      two: {
        selected: undefined,
      },
      three: {
        selected: undefined,
      }
    };

const arr = ['one', 'two'];

Object.keys(obj).map((item) => { 
       if(arr.includes(item)){
         obj[item].selected = true
       } else { 
        delete obj[item]
       }
     })

 console.log(obj)

answered Aug 9, 2018 at 13:08

Mohammed Ashfaq

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Comments

charlietfl · Accepted Answer · 2018-08-09 13:18:03Z

0

Using one line reduce()

const obj = {
      one: {
        selected: undefined,
      }, 
      two: {
        selected: undefined,
      },
      three: {
        selected: undefined,
      }
    };



const arr = ['one', 'two'];



const res = 
   arr.reduce((a,c) => (obj[c] && (a[c]= Object.assign({}, obj[c], {selected:true})),a),{});
 

console.log(res)

edited Aug 9, 2018 at 13:18

answered Aug 9, 2018 at 13:08

charlietfl

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