You have the ability to add javascript to your Showit site. When you have a page name selected, you will have the option to select the Advanced Settings tab in the right side Properties Panel. There you will find a handful of advanced options that will allow you to add snippets of code to your Showit site.
There are two options when it comes to adding Javascript: Inline Javascript and Page Loaded Javascript.
Inline Javascript
Inline Javascript will execute the code as the page loads. Ideally this would be used for functions that do not target specific interactions or elements on the page such as a button click. Inline Javascript would be used for functionality associated with tracking codes or something similar.
Page Loaded Javascript
Page Loaded Javascript will execute the code after the page has loaded. This would be used in the context of the code targeting certain interactions or elements on the page after those have had the opportunity to load.
Note: Both Inline and Page Loaded Javascript will, by default, wrap the code in <script> tags. Inputting your own <script> tags might cause issues with executing your code correctly.
Other Code Options
If you are looking to embed code in the <body> you can add it to any canvas through an embed widgets.
If you are looking to add code to the <head> or your site, you can find out how to do that here.