# babel-plugin-transform-es2015-duplicate-keys > Compile objects with duplicate keys to valid strict ES5. This plugin actually converts duplicate keys in objects to be computed properties, which then must be handled by the [transform-es2015-computed-properties](http://babeljs.io/docs/plugins/transform-es2015-computed-properties) plugin. The final result won't contain any object literals with duplicate keys. ## Example **In** ```javascript var x = { a: 5, a: 6 }; var y = { get a() {}, set a(x) {}, a: 3 }; ``` **Out** ```javascript var x = { a: 5, ["a"]: 6 }; var y = { get a() {}, set a(x) {}, ["a"]: 3 }; ``` ## Installation ```sh npm install --save-dev babel-plugin-transform-es2015-duplicate-keys ``` ## Usage ### Via `.babelrc` (Recommended) **.babelrc** ```json { "plugins": ["transform-es2015-duplicate-keys"] } ``` ### Via CLI ```sh babel --plugins transform-es2015-duplicate-keys script.js ``` ### Via Node API ```javascript require("babel-core").transform("code", { plugins: ["transform-es2015-duplicate-keys"] }); ```