```javascript
const DEBUG = false;
const PRODUCTION = true;
+// Alternative for environments that don't support `const`
+/** @const */ var STAGING = false;
// etc.
```
UglifyJS will notice the constants and, since they cannot be altered, it
will evaluate references to them to the value itself and drop unreachable
-code as usual. The possible downside of this approach is that the build
-will contain the `const` declarations.
+code as usual. The build will contain the `const` declarations if you use
+them. If you are targeting < ES6 environments, use `/** @const */ var`.
<a name="codegen-options"></a>
## Beautifier options