pretix_original/src/pretix/static/pretixbase/js/reldate.js

$(document).on('pretix:bind-forms', () => {
	document.querySelectorAll('.reldatetime, .reldate').forEach(container => {
		const groups = container.querySelectorAll('.radio')

		groups.forEach(group => {
			const referenceSelect = group.querySelector('select[data-relative-choice]')
			const beforeAfterSelect = group.querySelector('select[data-relation-choice]')
			if (!referenceSelect || !beforeAfterSelect) return

			const beforeOption = beforeAfterSelect.querySelector('option[value="before"]')
			const afterOption = beforeAfterSelect.querySelector('option[value="after"]')

			const updateBeforeOption = () => {
				let supportsBefore = referenceSelect.selectedOptions[0].hasAttribute('data-supports-before')
				if (beforeOption) {
					beforeOption.disabled = !beforeOption.disabled && !supportsBefore
				}

				let supportsAfter = referenceSelect.selectedOptions[0].hasAttribute('data-supports-after')
				if (afterOption) {
					afterOption.disabled = !afterOption.disabled && !supportsAfter
				}

				let dirty = false
				if (beforeOption.disabled && beforeAfterSelect.value === 'before') {
					beforeAfterSelect.value = 'after'
					dirty = true
				}
				if (afterOption.disabled && beforeAfterSelect.value === 'after') {
					beforeAfterSelect.value = 'before'
					dirty = true
				}

				if (dirty) {
					beforeAfterSelect.dispatchEvent(new Event('change', {bubbles: true}))
				}
			}
			referenceSelect.addEventListener('change', updateBeforeOption)
			updateBeforeOption()
		})
	})
})