A simple example of a way to auto refresh all data sources present on a Tableau dashboard at regular time intervals.
Download the RefreshAll.trex file from this repo and drag in the extension, select My Extension and select the downloaded .trex file.
Download the complete source repository, customize the JS and HTML if needed and host them in your web server. Update the url in the .trex file with the web server where extension is hosted.
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<url>https://yourcompany.com/autorefresh-datasources-tableau/</url>
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Main source for refreshing the data source is forked from https://github.com/KeshiaRose/refresh-all-example