Simple utility to create a object literal which has the same values as the key names.
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spec Make tests a bit more readable Aug 27, 2014
.gitignore Add grunt and build a browser version Jul 31, 2014
LICENSE Initial commit Jul 31, 2014 Bump version to v1.2.0 Aug 27, 2014
mirrorkey.js Oh the humanity, I had a double quote Aug 27, 2014
mirrorkey_browser.min.js Bump version to v1.2.0 Aug 27, 2014
package.json Bump version to v1.2.0 Aug 27, 2014


A small utility that takes a object literal and returns a new object literal whose values are the same as keys.

The idea came from react/utils/keyMirror but I added transforms which allows you to transform the values. There are 5 available transforms: none, camel-case, lower-case, dashed & lower-dashed. You pass the transform in as the second argument (default is none),

This utility is useful for creating maps of constants, as it helps you to avoid having to type the same thing twice.


var myConstants = {
	MY_FOO: null,
	MY_BAR: null


mirrorKey(myConstants, 'lower-dashed');
	MY_FOO: 'my-foo',
	MY_BAR: 'my-bar'

You can also pass in an array instead of an object:

mirrorKey(['MY_FOO', 'MY_BAR']);

// you can also use transforms as above if you pass in an array

Runtime support

Works in node.js and in the browser.

I haven't yet tested this in every browser, but it should work as I haven't used any >ES5 functions.


Node, Browserify & Webpack: npm install mirrorkey

Bower: bower install mirrorkey

Other: you can also just grap mirrorkey_browser.js or mirrorkey_browser.min.js and include them in your project manually. A global mirrorkey will be available on the window object.


Clone this repository. Source code is in mirrorkey.js and the tests are in spec/. To run the tests you will need to install jasmine-node with npm install jasmine-node -g. After which you can run npm test to run the tests.

If you wish to build a browser version then run npm install and then grunt which will generate the browser versions for you.


See LICENSE file.