The jsRendering option is used to force the engine to render pages loaded with Javascript.

There are 2 ways to call the option :

=IMPORTFROMWEB(data_sources, selectors, "jsRendering")


3=IMPORTFROMWEB(data_sources, selectors, A1:B1)

You can also pair jsRendering with the timeToWait option. timeToWait is the time in seconds that the function will wait until it looks for the data. It can be useful in case the looked up data takes a long time to load.

Example: Wait for 10 seconds

=IMPORTFROMWEB(data_sources, selectors, "jsRendering, timeToWait: 10")

For speed and resource consumption purposes, the engine does not run JavaScript on a page by default. You may need it if the function does not output the expected results.
You can also guess when a webpage uses Javascript: typically when a spinner is displayed while waiting for the data to load.

Note that rendering JavaScript content will generally take more time. If 30 seconds have passed, the function displays a #PENDING_REQUEST message while our server fetches the page.