chrome . runtime . onInstalled . addListener ( ( { reason , version } ) => { if ( reason === chrome . runtime . OnInstalledReason . INSTALL ) { showReadme ( ) ; } } ) ; chrome . action . onClicked . addListener ( ( tab ) => { showReadme ( ) ; } ) ; function showReadme ( info , tab ) { let url = chrome . runtime . getURL ( "readme.html" ) ; chrome . tabs . create ( { url } ) ; }