从对象中删除元素-javascript

Question

if I had an array of objects such as

const arrOfObj = [
    {
        'a': 'a', 
        'b': 'b', 
        'c': 'c',
        'd': 'd'
    }
 ]

how do I create a new array with an object that has only a and b?

 {
        'a': 'a', 
        'b': 'b'
 }

I've been trying something like

Object.entries(arrOfObjs[0]).filter(x => x[0] !== 'a' && x[0] !== 'b')

but there must be a simpler cleaner way

Answer 1

You can map the array, use destructuring and shorthand property names you're there:

const result = arrOfObj.map(({a, b}) => ({a, b}));

Example:

 const arrOfObj = [ { 'a': 'a', 'b': 'b', 'c': 'c', 'd': 'd' }, { 'a': 'aa', 'b': 'bb', 'c': 'cc', 'd': 'dd' }, { 'a': 'aaa', 'b': 'bbb', 'c': 'ccc', 'd': 'ddd' } ]; const result = arrOfObj.map(({a, b}) => ({a, b})); console.log(result); 

Answer 2

Destructuring syntax works nicely for this, as you can see in the other answer. However it requires a and b at the program level. If a and b exist at the data level, for example as values in array, the program would be slightly different

 const pick = (o = {}, keys = []) => keys .reduce ( (acc, k) => Object .assign (acc, { [k]: o[k] }) , {} ) const print = (...values) => values .forEach (x => console .log (x)) const data = { a: 1, b: 2, c: 3 } print ( pick (data, [ 'a', 'b' ]) // { a: 1, b: 2 } , pick (data, [ 'c', 'd' ]) // { c: 3, d: undefined } , pick (data, []) // {} , data // { a: 1, b: 2, c: 3 } ) 

As you can see, data is not mutated by use of pick .

Answer 3

Your title suggests that you want to remove specific properties, but the text suggests you actually want to keep specific ones. If it's the latter, I would suggest either the solution from ibrahim mahrir or the one from user633183.

But if it's the former, here is an approach similar to the one from user633183 but that creates a clone without the given properties:

 const omit = (keys = []) => (o = {}) => Object .keys (o) .reduce ( (acc, k) => keys .includes (k) ? acc : Object .assign (acc, { [k]: o[k] }) , {} ) const print = (...values) => values .forEach (x => console .log (x)) const data = { a: 1, b: 2, c: 3, d: 4 } print ( omit ([ 'c', 'd' ]) (data) // { a: 1, b: 2 } , omit ([ 'b' ]) (data) // { a: 1, c: 3, d: 4 } , omit ([ ]) (data) // { a: 1, b: 2, c: 3, d: 4 } , data // { a: 1, b: 2, c: 3, d: 4 } ) 

Answer 4

You can delete properties from an object.

 const arrOfObj = [ { 'a': 'a', 'b': 'b', 'c': 'c', 'd': 'd' } ]; console.log(arrOfObj.reduce((acc, val) => { let v = Object.assign({}, val); Object.keys(v).forEach(i => { if (i !== 'a' && i !== 'b') { delete v[i]; } }); acc.push(v); return acc; }, [])); console.log(arrOfObj); 

** Edited the above to stay more inline with the request.