SharePoint: Using JScript in calculated column (field) formula via CSR and JSLink

Article
1/17/2024

Introduction and problem

Calculated fields formulas are user-friendly and easy-to-start-using business logic containers in SharePoint.While the formulas are very spread there are some limitations and confusions like the "today" problem.

Numerous articles address the issues and use CSR (client-side rendering) as a convenient and recommended way to change the behavior at client rendering time.

The current article is intended to collect P&P (patterns and practices) for SharePoint calculated fields implementation via CSR and JSLink.

Sub problem: long-running calculations

One of the common problems while using CSR is a disability of direct access for field values that are not included in the view. A direct solution is to use CSOM (client side object model) to access the missing values but at the rendering time CSOM is not accessible and although we can still reach the values via synchronous REST ajax request it is not a recommended way and we are getting corresponding depreciation warning:

In the current article, we consider the CSR approach to implement common field value JScript calculation with long calculations(external requests) and use JSLink to implement the solution. As an example of external request REST ajax calls to reach missing field values are considered. The approach for external requests is an alternative for using SharePoint external columns.

Solution

The idea is pretty simple. We want to have minimal impact on the main rendering performance and we want to finish overall rendering as soon as possible.

Solution:

Starting the calculations as soon as possible. Putting it in the JScript queue or in the HTML5 web workers right after getting all the input information for the calculation. In our case it is the itemid which we reach at the field override rendering event.
-We render the calculated values in onpostrender event.