Initial commit

src/errors/DJSError.js

@@ -0,0 +1,61 @@
+'use strict';
+
+// Heavily inspired by node's `internal/errors` module
+
+const kCode = Symbol('code');
+const messages = new Map();
+
+/**
+ * Extend an error of some sort into a DiscordjsError.
+ * @param {Error} Base Base error to extend
+ * @returns {DiscordjsError}
+ */
+function makeDiscordjsError(Base) {
+  return class DiscordjsError extends Base {
+    constructor(key, ...args) {
+      super(message(key, args));
+      this[kCode] = key;
+      if (Error.captureStackTrace) Error.captureStackTrace(this, DiscordjsError);
+    }
+
+    get name() {
+      return `${super.name} [${this[kCode]}]`;
+    }
+
+    get code() {
+      return this[kCode];
+    }
+  };
+}
+
+/**
+ * Format the message for an error.
+ * @param {string} key Error key
+ * @param {Array<*>} args Arguments to pass for util format or as function args
+ * @returns {string} Formatted string
+ */
+function message(key, args) {
+  if (typeof key !== 'string') throw new Error('Error message key must be a string');
+  const msg = messages.get(key);
+  if (!msg) throw new Error(`An invalid error message key was used: ${key}.`);
+  if (typeof msg === 'function') return msg(...args);
+  if (!args?.length) return msg;
+  args.unshift(msg);
+  return String(...args);
+}
+
+/**
+ * Register an error code and message.
+ * @param {string} sym Unique name for the error
+ * @param {*} val Value of the error
+ */
+function register(sym, val) {
+  messages.set(sym, typeof val === 'function' ? val : String(val));
+}
+
+module.exports = {
+  register,
+  Error: makeDiscordjsError(Error),
+  TypeError: makeDiscordjsError(TypeError),
+  RangeError: makeDiscordjsError(RangeError),
+};