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About stdlib...

We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.

The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

mapKeys

NPM version Build Status Coverage Status

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

Usage

To use in Observable,

mapKeys = require( 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-map-keys@umd/browser.js' )

To vendor stdlib functionality and avoid installing dependency trees for Node.js, you can use the UMD server build:

var mapKeys = require( 'path/to/vendor/umd/utils-map-keys/index.js' )

To include the bundle in a webpage,

<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/utils-map-keys@umd/browser.js"></script>

If no recognized module system is present, access bundle contents via the global scope:

<script type="text/javascript">
(function () {
    window.mapKeys;
})();
</script>

mapKeys( obj, transform )

Maps 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

<!DOCTYPE html>
<html lang="en">
<body>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/utils-map-keys@umd/browser.js"></script>
<script type="text/javascript">
(function () {

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' }

})();
</script>
</body>
</html>

See Also

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.