Field rollup enables a calculated field for computing and storing sum of child items on parent destination field.
The extension has been tested and verified on Node v12.0.0 and above.
Building the extention
From the project root, run the following terminal commands:
This will produce the .vsix package file that you can upload to the Azure Marketplace or install on your on-prem extension gallery.
Auto calculated destination field on the work item parent
Because this extension requires the new work item form, it is only supported on Azure DevOps and the next version of TFS 2018 and above.