.browserslistrc

[modern]
# Modern builds target recent browsers supporting the latest features to minimize transpilation, polyfills, etc.
# It is served to browsers meeting the following requirements:
# - released in the last year + current alpha/beta versions
# - Firefox extended support release (ESR)
# - with global utilization at or above 0.5%
# - exclude dead browsers (no security maintenance for 2+ years)
# - exclude KaiOS, QQ, and UC browsers due to lack of sufficient feature support data
unreleased versions
last 1 year
Firefox ESR
>= 0.5%
not dead
not KaiOS > 0
not QQAndroid > 0
not UCAndroid > 0

[legacy]
# Legacy builds are served when modern requirements are not met and support browsers:
# - released in the last 7 years + current alpha/beta versionss
# - with global utilization at or above 0.05%
# - exclude dead browsers (no security maintenance for 2+ years)
# - exclude Opera Mini which does not support web sockets
unreleased versions
last 7 years
>= 0.05%
not dead
not op_mini all

[legacy-sw]
# Same as legacy plus supports service workers
unreleased versions
last 7 years
>= 0.05% and supports serviceworkers
not dead
not op_mini all