Nitpick refactor for courses command

commands/course.js

@@ -1,4 +1,5 @@
 const { SlashCommandBuilder } = require("@discordjs/builders");
+const { ChannelType } = require("discord.js");
 
 const COMMAND_JOIN = "join";
 const COMMAND_LEAVE = "leave";
@@ -35,20 +36,26 @@ const get_real_course_name = (course) => {
 };
 
 const is_valid_course = (course) => {
-    const reg_comp_course = /^comp\d{4}$/;
-    const reg_math_course = /^math\d{4}$/;
-    const reg_binf_course = /^binf\d{4}$/;
-    const reg_engg_course = /^engg\d{4}$/;
-    const reg_seng_course = /^seng\d{4}$/;
-    const reg_desn_course = /^desn\d{4}$/;
+    const reg_valid_course = /^[a-zA-Z]{4}\d{4}$/;
+
+    return reg_valid_course.test(course);
+};
+
+const is_supported_course = (course) => {
+    const reg_comp_course = /^comp\d{4}$/i;
+    const reg_math_course = /^math\d{4}$/i;
+    const reg_binf_course = /^binf\d{4}$/i;
+    const reg_engg_course = /^engg\d{4}$/i;
+    const reg_seng_course = /^seng\d{4}$/i;
+    const reg_desn_course = /^desn\d{4}$/i;
 
     return (
-        reg_comp_course.test(course.toLowerCase()) ||
-        reg_math_course.test(course.toLowerCase()) ||
-        reg_binf_course.test(course.toLowerCase()) ||
-        reg_engg_course.test(course.toLowerCase()) ||
-        reg_seng_course.test(course.toLowerCase()) ||
-        reg_desn_course.test(course.toLowerCase())
+        reg_comp_course.test(course) ||
+        reg_math_course.test(course) ||
+        reg_binf_course.test(course) ||
+        reg_engg_course.test(course) ||
+        reg_seng_course.test(course) ||
+        reg_desn_course.test(course)
     );
 };
 
@@ -87,20 +94,20 @@ module.exports = {
                 const input_course = await interaction.options.getString("course").toLowerCase();
                 const course = get_real_course_name(input_course);
 
-                const other_courses = /^[a-zA-Z]{4}\d{4}$/;
                 const is_valid = is_valid_course(course);
+                const is_supported = is_supported_course(course);
 
                 const course_with_alias =
                     course != input_course
                         ? `${course} (same course chat as ${input_course})`
                         : `${course}`;
 
-                if (!is_valid && other_courses.test(course.toLowerCase())) {
+                if (!is_supported && is_valid) {
                     return await interaction.reply({
                         content: `❌ | Course chats for other faculties are not supported.`,
                         ephemeral: true,
                     });
-                } else if (!is_valid) {
+                } else if (!is_supported) {
                     return await interaction.reply({
                         content: `❌ | You are not allowed to join this channel using this command.`,
                         ephemeral: true,
@@ -138,7 +145,7 @@ module.exports = {
                 const input_course = await interaction.options.getString("course");
                 const course = get_real_course_name(input_course);
 
-                if (!is_valid_course(course)) {
+                if (!is_supported_course(course)) {
                     return await interaction.reply({
                         content: `❌ | Not a valid course.`,
                         ephemeral: true,
@@ -155,7 +162,7 @@ module.exports = {
                         content: `❌ | The course chat for \`${course}\` does not exist.`,
                         ephemeral: true,
                     });
-                } else if (channel.type !== "GUILD_TEXT") {
+                } else if (channel.type !== ChannelType.GuildText) {
                     return await interaction.reply({
                         content: `❌ | The course chat for \`${course}\` is not a text channel.`,
                         ephemeral: true,