switchInstance returns next instance instead of random

src/assets/javascripts/services.js

@@ -605,7 +605,7 @@ function switchInstance(url, customService) {
 		if (customService) {
 			const instancesList = options[options[customService].frontend]
 			if (instancesList !== undefined) {
-				resolve(`${utils.getRandomInstance(instancesList)}${url.pathname}${url.search}`)
+				resolve(`${utils.getNextInstance(url.origin, instancesList)}${url.pathname}${url.search}`)
 			}
 		} else {
 			for (const service in config.services) {
@@ -618,7 +618,7 @@ function switchInstance(url, customService) {
 					resolve()
 					return
 				}
-				resolve(`${utils.getRandomInstance(instancesList)}${url.pathname}${url.search}`)
+				resolve(`${utils.getNextInstance(url.origin, instancesList)}${url.pathname}${url.search}`)
 				return
 			}
 		}

src/assets/javascripts/utils.js

@@ -8,6 +8,23 @@ function getRandomInstance(instances) {
 	return instances[~~(instances.length * Math.random())]
 }
 
+/**
+ * @param {string} currentInstanceUrl
+ * @param {Array.<T>} instances
+ * @returns {T}
+ */
+function getNextInstance(currentInstanceUrl, instances) {
+	const currentInstanceIndex = instances.indexOf(currentInstanceUrl);
+
+	if (currentInstanceIndex === -1){
+		return getRandomInstance(instances);
+	}
+
+	const nextInstanceIndex = (currentInstanceIndex + 1) % instances.length;
+
+	return instances[nextInstanceIndex];
+}
+
 /**
  * @param {string} str
  */
@@ -195,6 +212,7 @@ function ping(href) {
 
 export default {
 	getRandomInstance,
+	getNextInstance,
 	protocolHost,
 	getList,
 	getBlacklist,