small-packages/luci-app-ssr-plus/luasrc/view/shadowsocksr/client_dns_defaults.htm

<script type="text/javascript">
//<![CDATA[
(function() {
	function getField(name) {
		return document.querySelector('select[name$=".' + name + '"], input[name$=".' + name + '"]');
	}

	function ensureDefaultValue(modeValue, fieldName) {
		var modeEl = getField('pdnsd_enable');
		var dnsEl = getField(fieldName);
		if (!modeEl || !dnsEl || modeEl.value !== modeValue) {
			return;
		}

		var current = (dnsEl.value || '').trim();
		var placeholder = (dnsEl.options && dnsEl.selectedIndex >= 0 && dnsEl.options[dnsEl.selectedIndex])
			? (dnsEl.options[dnsEl.selectedIndex].text || '').trim()
			: '';
		if (current !== '' && current !== '-- 请选择 --' && current !== '-- Please choose --' &&
			placeholder !== '-- 请选择 --' && placeholder !== '-- Please choose --') {
			return;
		}

		if (dnsEl.tagName === 'SELECT') {
			var firstValue = '';
			for (var i = 0; i < dnsEl.options.length; i++) {
				var option = dnsEl.options[i];
				if (option && option.value) {
					firstValue = option.value;
					break;
				}
			}
			if (firstValue) {
				dnsEl.value = firstValue;
			}
		} else if (dnsEl.dataset && dnsEl.dataset.default) {
			dnsEl.value = dnsEl.dataset.default;
		}
	}

	function ensureMosdnsDefault() {
		ensureDefaultValue('4', 'tunnel_forward_mosdns');
	}

	function ensureChinaDnsNgDefault() {
		ensureDefaultValue('6', 'chinadns_ng_tunnel_forward');
	}

	function bindModeChange() {
		var modeEl = getField('pdnsd_enable');
		if (!modeEl || modeEl.dataset.ssrDnsDefaultBound) {
			return;
		}

		modeEl.dataset.ssrDnsDefaultBound = '1';
		modeEl.addEventListener('change', function() {
			window.setTimeout(function() {
				ensureMosdnsDefault();
				ensureChinaDnsNgDefault();
			}, 0);
		});
	}

	function initMosdnsDefault() {
		bindModeChange();
		ensureMosdnsDefault();
		ensureChinaDnsNgDefault();
	}

	if (document.readyState === 'loading') {
		document.addEventListener('DOMContentLoaded', initMosdnsDefault);
		window.addEventListener('load', initMosdnsDefault);
	} else {
		initMosdnsDefault();
	}
})();
//]]>
</script>