Return all nested objects with specific keys-CodePudding

I have an array of objects in Javascript:

[
{a: 1, b: 2, c: 4},
{d: 10, a: 9, r: 2},
{c: 5, e: 2, j: 41}
]

I would like to return an array of all the objects that have the key name c by using the key name for the lookup.

What is the best way to accomplish this?

CodePudding user response：

the easiest way is to loop through the array to check if the object has a key named c

var arr = [
    { a: 1, b: 2, c: 4 },
    { d: 10, a: 9, r: 2 },
    { c: 5, e: 2, j: 41 }
]

// they both do the same job
var result = arr.filter(item => Object.keys(item).some(key => key.indexOf('c') > -1))
var filtered = arr.filter(item => item.hasOwnProperty('c'))


console.log(result);
console.log(filtered);

CodePudding user response：

Try using filter and hasOwnProperty.

const data = [{
    a: 1, b: 2, c: 4
  },
  {
    d: 10, a: 9, r: 2
  },
  {
    c: 5,  e: 2, j: 41
  }
];

const filtered = (arr, prop) =>
  arr.filter(a => a.hasOwnProperty(prop));
  
console.log(
  JSON.stringify(filtered(data, 'c'))
);

If you want to return an array of objects with multiple specific keys, you can combine it with some.

const data = [{
    a: 1, b: 2, c: 4
  },
  {
    d: 10, a: 9, r: 2
  },
  {
    c: 5,  e: 2, j: 41
  }
];
  
const filtered = (arr, ...props) =>
  arr.filter(a => props.some(prop => a.hasOwnProperty(prop)));

console.log(
  JSON.stringify(filtered(data, 'b', 'j'))
);

CodePudding user response：

use filter(), and maybe hasOwnProperty() or another way to check if the property is present on the object.

const myarray = [
    { a: 1, b: 2, c: 4 },
    { d: 10, a: 9, r: 2 },
    { c: 5, e: 2, j: 41 }
];

const processedarray = myarray.filter( item => item.hasOwnProperty( 'c' ) );

console.log( processedarray );

CodePudding user response：

var arr = [
{a: 1, b: 2, c: 4},
{d: 10, a: 9, r: 2},
{c: 5, e: 2, j: 41}
];
var result = arr.filter((x)=> 'c' in x);
console.log(result)

CodePudding user response：

This is My answer. Thank you

const arr = [
  {a: 1, b: 2, c: 4},
  {d: 10, a: 9, r: 2},
  {c: 5, e: 2, j: 41}
]

const filter = (arr, byKey) => {
  return arr.filter((ob) => {
    return Object.keys(ob).includes(byKey)
  })
}

console.log(filter(arr, 'c'))