1 files changed, 21 insertions, 11 deletions

diff --git a/src/content/follow.js b/src/content/follow.js
index ffa16b9..5abeee0 100644
--- a/src/content/follow.js
+++ b/src/content/follow.js
@@ -1,7 +1,7 @@
 import Hint from './hint';
 import HintKeyProducer from './hint-key-producer';
 
-const DEFAULT_HINT_CHARSET = 'abcdefghijklmnopqrstuvwxyz'
+const DEFAULT_HINT_CHARSET = 'abcdefghijklmnopqrstuvwxyz';
 
 export default class Follow {
   constructor(doc) {
@@ -22,14 +22,14 @@ export default class Follow {
     let producer = new HintKeyProducer(DEFAULT_HINT_CHARSET);
     Array.prototype.forEach.call(elements, (ele) => {
       let keys = producer.produce();
-      let hint = new Hint(ele, keys)
+      let hint = new Hint(ele, keys);
 
       this.hintElements[keys] = hint;
     });
   }
 
   handleKeydown(e) {
-    let keyCode = e.keyCode;
+    let { keyCode } = e;
     if (keyCode === KeyboardEvent.DOM_VK_ESCAPE) {
       this.remove();
       return;
@@ -56,10 +56,10 @@ export default class Follow {
     let hidden = Object.keys(this.hintElements).filter((key) => {
       return !key.startsWith(chars);
     });
-    if (shown.length == 0) {
+    if (shown.length === 0) {
       this.remove();
       return;
-    } else if (shown.length == 1) {
+    } else if (shown.length === 1) {
       this.remove();
       this.hintElements[chars].activate();
     }
@@ -74,7 +74,7 @@ export default class Follow {
 
 
   remove() {
-    this.doc.removeEventListener("keydown", this.boundKeydown);
+    this.doc.removeEventListener('keydown', this.boundKeydown);
     Object.keys(this.hintElements).forEach((key) => {
       this.hintElements[key].remove();
     });
@@ -87,6 +87,14 @@ export default class Follow {
     );
   }
 
+  static isNumericKey(code) {
+    return KeyboardEvent.DOM_VK_0 <= code && code <= KeyboardEvent.DOM_VK_9;
+  }
+
+  static isAlphabeticKey(code) {
+    return KeyboardEvent.DOM_VK_A <= code && code <= KeyboardEvent.DOM_VK_Z;
+  }
+
   static codeChars(codes) {
     const CHARCODE_ZERO = '0'.charCodeAt(0);
     const CHARCODE_A = 'a'.charCodeAt(0);
@@ -94,10 +102,12 @@ export default class Follow {
     let chars = '';
 
     for (let code of codes) {
-      if (KeyboardEvent.DOM_VK_0 <= code && code <= KeyboardEvent.DOM_VK_9) {
-        chars += String.fromCharCode(code - KeyboardEvent.DOM_VK_0 + CHARCODE_ZERO);
-      } else if (KeyboardEvent.DOM_VK_A <= code && code <= KeyboardEvent.DOM_VK_Z) {
-        chars += String.fromCharCode(code - KeyboardEvent.DOM_VK_A + CHARCODE_A);
+      if (Follow.isNumericKey(code)) {
+        chars += String.fromCharCode(
+          code - KeyboardEvent.DOM_VK_0 + CHARCODE_ZERO);
+      } else if (Follow.isAlphabeticKey(code)) {
+        chars += String.fromCharCode(
+          code - KeyboardEvent.DOM_VK_A + CHARCODE_A);
       }
     }
     return chars;
@@ -112,7 +122,7 @@ export default class Follow {
   }
 
   static isVisibleElement(element) {
-    var style = window.getComputedStyle(element);
+    let style = window.getComputedStyle(element);
     if (style.display === 'none') {
       return false;
     } else if (style.visibility === 'hidden') {