mapKeys

Map keys from one object to a new object having the same values.

Usage

var mapKeys = require( '@stdlib/utils/map-keys' );

mapKeys( obj, transform )

Map keys from one object to a new object having the same values.

function transform( key, value ) {
    return key + value;
}

var obj1 = {
    'a': 1,
    'b': 2
};

var obj2 = mapKeys( obj1, transform );
// returns { 'a1': 1, 'b2': 2 }

The transform function is provided three arguments:

  • key: object key
  • value: object value corresponding to key
  • obj: the input object

Notes

  • Key iteration order is not guaranteed, as object key enumeration is not specified according to the ECMAScript specification. In practice, however, most engines use insertion order to sort an object's keys, thus allowing for deterministic return values.
  • The function only maps own properties. Hence, the function does not map inherited properties.
  • The function shallow copies key values.
  • The value returned by a transform function should be a value which can be serialized as an object key.

Examples

var mapKeys = require( '@stdlib/utils/map-keys' );

function transform( key, value ) {
    return key + ':' + value;
}

var obj1 = {
    'a': 'beep',
    'b': 'boop',
    'c': 'foo',
    'd': 'bar'
};

var obj2 = mapKeys( obj1, transform );

console.dir( obj2 );
// => { 'a:beep': 'beep', 'b:boop': 'boop', 'c:foo': 'foo', 'd:bar': 'bar' }