fix(meta-key): fix edge cases for meta key usage. (#761)

lib/hterm.js

@@ -1,4 +1,5 @@
 import {hterm, lib} from 'hterm-umdjs';
+import fromCharCode from './utils/key-code';
 
 const selection = require('./utils/selection');
 
@@ -39,6 +40,8 @@ hterm.Terminal.prototype.copySelectionToClipboard = function () {
 // hyperterm and not the terminal itself
 const oldKeyDown = hterm.Keyboard.prototype.onKeyDown_;
 hterm.Keyboard.prototype.onKeyDown_ = function (e) {
+  const modifierKeysConf = this.terminal.modifierKeys;
+
   /**
    * Add fixes for U.S. International PC Keyboard layout
    * These keys are sent through as 'Dead' keys, as they're used as modifiers.
@@ -58,7 +61,7 @@ hterm.Keyboard.prototype.onKeyDown_ = function (e) {
       return;
     }
     // This key is also a tilde on all tested keyboards
-    if (e.code === 'KeyN' && e.altKey === true) {
+    if (e.code === 'KeyN' && e.altKey === true && modifierKeysConf.altIsMeta === false) {
       this.terminal.onVTKeystroke('~');
       return;
     }
@@ -80,11 +83,11 @@ hterm.Keyboard.prototype.onKeyDown_ = function (e) {
       return;
     }
     // Italian keyboard layout
-    if (e.code === 'Digit9' && e.altKey === true) {
+    if (e.code === 'Digit9' && e.altKey === true && modifierKeysConf.altIsMeta === false) {
       this.terminal.onVTKeystroke('`');
       return;
     }
-    if (e.code === 'Digit8' && e.altKey === true) {
+    if (e.code === 'Digit8' && e.altKey === true && modifierKeysConf.altIsMeta === false) {
       this.terminal.onVTKeystroke('´');
       // To fix issue with changing the terminal prompt
       e.preventDefault();
@@ -102,21 +105,27 @@ hterm.Keyboard.prototype.onKeyDown_ = function (e) {
     console.warn('Uncaught dead key on international keyboard', e);
   }
 
-  const modifierKeysConf = this.terminal.modifierKeys;
   if (e.altKey &&
-      e.code !== 'alt' &&
-      e.code !== 'altLeft' &&
-      e.code !== 'altRight' &&
+      e.which !== 16 && // Ignore other modifer keys
+      e.which !== 17 &&
+      e.which !== 18 &&
+      e.which !== 91 &&
       modifierKeysConf.altIsMeta) {
-    this.terminal.onVTKeystroke('\x1b' + String.fromCharCode(e.keyCode));
+    const char = fromCharCode(e);
+    this.terminal.onVTKeystroke('\x1b' + char);
     e.preventDefault();
   }
 
   if (e.metaKey &&
       e.code !== 'MetaLeft' &&
       e.code !== 'MetaRight' &&
+      e.which !== 16 &&
+      e.which !== 17 &&
+      e.which !== 18 &&
+      e.which !== 91 &&
       modifierKeysConf.cmdIsMeta) {
-    this.terminal.onVTKeystroke('\x1b' + String.fromCharCode(e.keyCode));
+    const char = fromCharCode(e);
+    this.terminal.onVTKeystroke('\x1b' + char);
     e.preventDefault();
   }
 

lib/utils/key-code.js

@@ -0,0 +1,79 @@
+/**
+ * Keyboard event keyCodes have proven to be really unreliable.
+ * This util function will cover most of the edge cases where
+ * String.fromCharCode() will not work
+ */
+
+const _toAscii = {
+  '188': '44',
+  '109': '45',
+  '190': '46',
+  '191': '47',
+  '192': '96',
+  '220': '92',
+  '222': '39',
+  '221': '93',
+  '219': '91',
+  '173': '45',
+  '187': '61', // IE Key codes
+  '186': '59', // IE Key codes
+  '189': '45'  // IE Key codes
+};
+
+const _shiftUps = {
+  '96': '~',
+  '49': '!',
+  '50': '@',
+  '51': '#',
+  '52': '$',
+  '53': '%',
+  '54': '^',
+  '55': '&',
+  '56': '*',
+  '57': '(',
+  '48': ')',
+  '45': '_',
+  '61': '+',
+  '91': '{',
+  '93': '}',
+  '92': '|',
+  '59': ':',
+  '39': '\'',
+  '44': '<',
+  '46': '>',
+  '47': '?'
+};
+
+const _arrowKeys = {
+  '38': '',
+  '40': '',
+  '39': '',
+  '37': ''
+};
+
+/**
+ * This fn takes a keyboard event and returns
+ * the character that was pressed. This fn
+ * purposely doens't take into account if the alt/meta
+ * key was pressed.
+ */
+export default function fromCharCode(e) {
+  let code = String(e.which);
+
+  if ({}.hasOwnProperty.call(_arrowKeys, code)) {
+    return _arrowKeys[code];
+  }
+
+  if ({}.hasOwnProperty.call(_toAscii, code)) {
+    code = _toAscii[code];
+  }
+
+  const char = String.fromCharCode(code);
+  if (e.shiftKey) {
+    if ({}.hasOwnProperty.call(_shiftUps, code)) {
+      return _shiftUps[code];
+    }
+    return char.toUpperCase();
+  }
+  return char.toLowerCase();
+}