# Edit Theme JavaScript

{% hint style="warning" %}
**We do not support code customizations**. This guide offers a basic reference for developers. Always test code changes on unpublished theme copies. For assistance, we recommend reaching out to a [verified Fluorescent partner](https://partners.fluorescent.co/).
{% endhint %}

{% hint style="info" %}
If you want to modify only a few components and retain code splitting, consider using Spark's standalone file for [custom JavaScript events](https://help.fluorescent.co/spark/for-developers/custom-javascript-events).
{% endhint %}

Spark includes a single, editable JavaScript file (**`assets/theme.js`**) for custom development that can be enabled in the **`snippets/theme-globals.liquid`** file.

Switching to the unminified **`theme.js`** disables code splitting, which bundles the theme JavaScript into multiple files used for lazy-loading and improved site performance. We do not recommend editing these files directly.

### Switch to theme.js

***

The **`theme.js`** file, when enabled, lets you edit a single JavaScript file, instead of many files, and includes comments from our developers to help you along.

<details>

<summary><mark style="color:blue;"><strong>STEPS</strong></mark></summary>

Open the **`theme-globals.liquid`** file in the **Snippets** folder.

1. Find the **`useUnminThemeJS`** variable and set it to **`true`**

{% code overflow="wrap" %}

```
```

{% endcode %}

\`\`\`json

````
{% assign useUnminThemeJS = false %}


```
````

2\. You can now begin editing the \*\*\`theme.js\`\*\* file in the \*\*Assets\*\* folder.

```
> We highly recommend backing up your theme and documenting any additions for troubleshooting and theme updates, which require manually transferring the code.
```

</details>

> **How's Spark working for you?**
>
> We built Spark with developers in mind. We're looking to create relationships with third-party developers using our themes and want to hear from you about what you're building. Please feel free to reach out with questions or introduce yourself by e-mailing us at <developers@fluorescent.co>

***

> **Related links**
>
> [Custom JavaScript events](https://help.fluorescent.co/spark/for-developers/custom-javascript-events)\
> [Custom Liquid](https://help.fluorescent.co/spark/for-developers/custom-liquid)\
> [Custom CSS](https://help.fluorescent.co/spark/for-developers/custom-css)\
> [Custom fonts](https://help.fluorescent.co/spark/for-developers/custom-fonts)