keyBy not support index

[wongest]

VERSION 4.17.21

Hope to support the index of the iterator

Example

keyBy(['a', 'b'], (_, index) => index);

Expected Result

{
  0: 'a',
  1: 'b',
}

Actual Result

{
  undefined: 'b',
}

[vincediegane]

You can try with this for the time being.

Example

const array1 = ['a', 'b'];

const array2 = [
  { 'dir': 'left', 'code': 97 },
  { 'dir': 'right', 'code': 100 }
];

console.log( keyBy(array1, _ => array1.indexOf(_)) );

console.log( keyBy(array2, _ => array2.indexOf(_)) );

Actual Result

 {
   0: 'a',
   1: 'b'
 }
 
 { 
   0: { dir: 'left', code: 97 },
   1: { dir: 'right', code: 100 }
 }

[sid0-0]

Raised a pull request (#5798).