As per WEB standard, a webpage should contain only a single element with an ID. But in Pega, it is possible to occur multiple times if we refer the same properties in a section multiple times if we keep the property name as ID. This is one of the reasons. To overcome this, they are generating unique IDs to the DOM elements.

Let me come to the point.

Pega uses Jquery. So, we can utilize that to make DOM operations simpler. Here is the code for selecting custom attributes elements using Jquery.

$('input[data-test-id="street_number"]')

Change data-test-id with a custom tag if want to change and street_number for value. To access the value, use val() function to access it. 

$('input[data-test-id="street_number"]').val();

But to access property values, I would suggest you go with the "name" attribute which will be formed based on clipboard page, understandable and doesn't change with rule versions. 

To refer name attribute, use the below snippet.

$('input[name="$PpyDisplayHarness$ppySearchText"]').val();

I hope it helps you!