从对象数组返回值

Question

I have the following structure

   const objArray = [ { shiftId: 89192 },
       { shiftId: 89193 },
       { shiftId: 89190 } ]

An array of objects. I am trying to map over and extract the value of the shiftId

What I do is object.map(el=> Object.values(el)); but this mapping returns the following structure because Object.values returns an array unfortunately.

[ [ 89192 ], [ 89193 ], [ 89190 ] ]

Nested arrays with only one element. How can I map over this to only back an array.

Answer 1

If you want to extract the shiftId property, just specify that you want to extract that particular property, rather than using Object.values :

const shiftIds = object.map(({ shiftId }) => shiftId);

Note that you have an array there - your code would be more understandable if you called the variable arrOfShiftObjs or something like that, rather than calling it object .

To extract multiple values from each item and put them into a single larger array, use flatMap :

 const arr = [{ shiftId: 89192, id: 'id' }, { shiftId: 89193, id: 'id' }, { shiftId: 89190, id: 'id' } ]; const values = arr.flatMap(Object.values); console.log(values);

Or, if the objects also contain other properties that you don't want to include, and you only want shiftId and id :

 const arr = [{ shiftId: 89192, id: 'id' }, { shiftId: 89193, id: 'id' }, { shiftId: 89190, id: 'id' } ]; const values = arr.flatMap(({ shiftId, id }) => [shiftId, id]); console.log(values);

Like the use of all newer functions, if you want to support browsers which don't have it yet, use a polyfill. Of course, you could also reduce instead

 const arr = [{ shiftId: 89192, id: 'id' }, { shiftId: 89193, id: 'id' }, { shiftId: 89190, id: 'id' } ]; const values = arr.reduce((a, { shiftId, id }) => { a.push(shiftId, id); return a; }, []); console.log(values);

Answer 2

You could get the property from the first found value.

 var array = [{ anonymous: { shiftId: 89192 } }, { anonymous: { shiftId: 89193 } }, { anonymous: { shiftId: 89190 } }], values = array.map(o => Object.values(o)[0].shiftId); console.log(values);

Answer 3

Using Object destructuring and Array.prototype.map

 let array = [{ anonymous: { shiftId: 89192 } }, { anonymous: { shiftId: 89193 } }, { anonymous: { shiftId: 89190 } }] let out = array.map(({anonymous: {shiftId}}) => shiftId) console.log(out)