wikimedia/mediawiki-core

/*
 * HTMLForm enhancements:
 * Enable the "Fill in from browser" option for the timezone selector
 */
function minutesToHours( min ) {
    const tzHour = Math.floor( Math.abs( min ) / 60 ),
        tzMin = Math.abs( min ) % 60,
        tzString = ( ( min >= 0 ) ? '' : '-' ) + ( ( tzHour < 10 ) ? '0' : '' ) + tzHour +
            ':' + ( ( tzMin < 10 ) ? '0' : '' ) + tzMin;
    return tzString;
}

mw.hook( 'htmlform.enhance' ).add( ( $root ) => {
    mw.loader.using( 'mediawiki.widgets.SelectWithInputWidget', () => {
        $root.find( '.mw-htmlform-timezone-field' ).each( function () {
            // This is identical to OO.ui.infuse( ... ), but it makes the class name of the result known.
            const timezoneWidget = mw.widgets.SelectWithInputWidget.static.infuse( $( this ) );

            function maybeGuessTimezone() {
                if ( timezoneWidget.dropdowninput.getValue() !== 'guess' ) {
                    return;
                }
                // If available, get the named time zone from the browser.
                // (We also support older browsers where this API is not available.)
                let timeZone;
                try {
                    // This may return undefined
                    timeZone = Intl.DateTimeFormat().resolvedOptions().timeZone;
                } catch ( err ) {
                    timeZone = null;
                }

                // Get the time offset
                const minuteDiff = -( new Date().getTimezoneOffset() );

                let newValue;
                if ( timeZone ) {
                    // Try to save both time zone and offset
                    newValue = 'ZoneInfo|' + minuteDiff + '|' + timeZone;
                    timezoneWidget.dropdowninput.setValue( newValue );
                }
                if ( !timeZone || timezoneWidget.dropdowninput.getValue() !== newValue ) {
                    // No time zone, or it's unknown to MediaWiki. Save only offset
                    timezoneWidget.dropdowninput.setValue( 'other' );
                    timezoneWidget.textinput.setValue( minutesToHours( minuteDiff ) );
                }
            }

            timezoneWidget.dropdowninput.on( 'change', maybeGuessTimezone );
            maybeGuessTimezone();
        } );
    } );
} );