When you have a List Block and a List Details block on the same page, LoadDefaultRecord ensures that the List Details block displays a default record when no record ID is specified on the URL.

How To Use It

In your the Code Inside Header section of your page settings, put the following code:
<script src="https://scissors.appspan.net/LoadDefaultRecord/LoadDefaultRecord.js">

How to Customize It

Add the following before the <script src=> tag:
const LoadDefaultRecord = {
defaultRecordId: "abc123" // Id of the record to display when no record Id is on the URL

What It Does

When the page loads, this script looks to see if there is a record Id specified on the URL, which could either be in the ?recordId= format or in the /r/rec format. If there is no record Id in either of these formats, then it changes the URL to include the value of defaultRecordId and reloads the page by calling history.replaceState() so that there is not an extra entry in the history.

Read the Code