# How to Modify Ember Route Class

**URL:** https://meta.discourse.org/t/how-to-modify-ember-route-class/143684
**Category:** Development
**Created:** [March 9, 2020, 11:06am UTC](https://meta.discourse.org/t/how-to-modify-ember-route-class/143684 "2020-03-09T11:06:32Z")
**Posts on this page:** 1
**Showing post:** 4

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### Author: ![Johani](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/johani/32/176920_2.png) [@Johani](https://meta.discourse.org/u/Johani)
#### Post date: [March 10, 2020, 10:12pm UTC](https://meta.discourse.org/t/how-to-modify-ember-route-class/143684/4 "2020-03-10T22:12:09Z")

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> [@saurabhmasc](#):
>
> ReferenceError: Composer is not defined

This happens because `Composer` is not defined in your code. If you look at the `tags-show` route, you’ll see that `Composer` is defined at the top.

[https://github.com/discourse/discourse/blob/master/app/assets/javascripts/discourse/routes/tags-show.js.es6#L2](https://github.com/discourse/discourse/blob/master/app/assets/javascripts/discourse/routes/tags-show.js.es6#L2)

However, since you’re doing this in theme script tags, you can’t use `import`. You’ll have to use `require` instead.

So, it should work if you add something like this to the top of your code

```plaintext
const Composer = require("discourse/models/composer");

```

That said, I strongly recommend that you spend a bit of time reading

> [@Split up theme Javascript into multiple files](https://meta.discourse.org/t/splitting-up-theme-javascript-into-multiple-files/119369):
>
> Complex theme javascript can be split into multiple files, to keep things nicely organised. To use this functionality, simply add files to the /javascripts folder in your theme directory. These files can not be edited from the Discourse UI, so you must use the [Theme CLI](https://meta.discourse.org/t/discourse-theme-cli-console-app-to-help-you-build-themes/82950) or [source the theme from git](https://meta.discourse.org/t/how-to-source-a-theme-from-a-private-git-repository/82584). Javascript files are treated exactly the same as they are in core/plugins, so you should follow the same file/folder structure. Theme files are loaded after core/plugins, so if the filenames match,…

and experimenting with this new way of creating themes. It’s much easier to follow examples in core that way.

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