fix: first check if string is ASCII

lib/rules/id-length.js

@@ -11,7 +11,44 @@
 //------------------------------------------------------------------------------
 const GraphemeSplitter = require("grapheme-splitter");
 
-const splitter = new GraphemeSplitter();
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+/**
+ * Checks if the string given as argument is ASCII or not.
+ * @param {string} value A string that you want to know if it is ASCII or not.
+ * @returns {boolean} `true` if `value` is ASCII string.
+ */
+function isASCII(value) {
+    if (typeof value !== "string") {
+        return false;
+    }
+    for (let i = 0; i < value.length; i++) {
+        if (value.charCodeAt(i) > 127) {
+            return false;
+        }
+    }
+    return true;
+}
+
+/** @type {GraphemeSplitter | undefined} */
+let splitter;
+
+/**
+ * Gets the length of the string. If the string is not in ASCII, counts graphemes.
+ * @param {string} value A string that you want to get the length.
+ * @returns {number} The length of `value`.
+ */
+function getStringLength(value) {
+    if (isASCII(value)) {
+        return value.length;
+    }
+    if (!splitter) {
+        splitter = new GraphemeSplitter();
+    }
+    return splitter.countGraphemes(value);
+}
 
 //------------------------------------------------------------------------------
 // Rule Definition
@@ -137,7 +174,7 @@ module.exports = {
                 const name = node.name;
                 const parent = node.parent;
 
-                const nameLength = splitter.countGraphemes(name);
+                const nameLength = getStringLength(name);
 
                 const isShort = nameLength < minLength;
                 const isLong = nameLength > maxLength;