diff --git a/app/assets/javascripts/discourse/lib/autocomplete.js.es6 b/app/assets/javascripts/discourse/lib/autocomplete.js.es6
index b8110dd3d..b34bbc7e9 100644
--- a/app/assets/javascripts/discourse/lib/autocomplete.js.es6
+++ b/app/assets/javascripts/discourse/lib/autocomplete.js.es6
@@ -6,44 +6,26 @@
 
 export var CANCELLED_STATUS = "__CANCELLED";
 
-var shiftMap = [];
-shiftMap[192] = "~";
-shiftMap[49] = "!";
-shiftMap[50] = "@";
-shiftMap[51] = "#";
-shiftMap[52] = "$";
-shiftMap[53] = "%";
-shiftMap[54] = "^";
-shiftMap[55] = "&";
-shiftMap[56] = "*";
-shiftMap[57] = "(";
-shiftMap[48] = ")";
-shiftMap[109] = "_";
-shiftMap[107] = "+";
-shiftMap[219] = "{";
-shiftMap[221] = "}";
-shiftMap[220] = "|";
-shiftMap[59] = ":";
-shiftMap[222] = "\"";
-shiftMap[188] = "<";
-shiftMap[190] = ">";
-shiftMap[191] = "?";
-shiftMap[32] = " ";
-
-function mapKeyPressToActualCharacter(isShiftKey, characterCode) {
-  if ( characterCode === 27 || characterCode === 8 || characterCode === 9 || characterCode === 20 || characterCode === 16 || characterCode === 17 || characterCode === 91 || characterCode === 13 || characterCode === 92 || characterCode === 18 ) { return false; }
-
-  // Lookup non-letter keypress while holding shift
-  if (isShiftKey && ( characterCode < 65 || characterCode > 90 )) {
-    return shiftMap[characterCode];
-  }
-
-  var stringValue = String.fromCharCode(characterCode);
-  if ( !isShiftKey ) {
-    stringValue = stringValue.toLowerCase();
-  }
-  return stringValue;
-}
+var Keys = {
+  BackSpace: 8,
+  Tab: 9,
+  Enter: 13,
+  Shift: 16,
+  Ctrl: 17,
+  Alt: 18,
+  Esc: 27,
+  Space: 32,
+  LeftWindows: 91,
+  RightWindows: 92,
+  PageUp: 33,
+  PageDown: 34,
+  End: 35,
+  Home: 36,
+  LeftArrow: 37,
+  UpArrow: 38,
+  RightArrow: 39,
+  DownArrow: 40,
+};
 
 export default function(options) {
   var autocompletePlugin = this;
@@ -78,9 +60,14 @@ export default function(options) {
     }
     div = null;
     completeStart = null;
+    completeEnd = null;
     autocompleteOptions = null;
   };
 
+  var autoCompleting = function () {
+    return completeStart !== null;
+  };
+
   var addInputSelectedItem = function(item) {
     var transformed,
         transformedItem = item;
@@ -131,7 +118,7 @@ export default function(options) {
           term = options.transformComplete(term);
         }
         var text = me.val();
-        text = text.substring(0, completeStart) + (options.key || "") + term + ' ' + text.substring(completeEnd + 1, text.length);
+        text = text.substring(0, completeStart) + term + ' ' + text.substring(completeEnd, text.length);
         me.val(text);
         Discourse.Utilities.setCaretPosition(me[0], completeStart + 1 + term.length);
       }
@@ -264,24 +251,37 @@ export default function(options) {
     closeAutocomplete();
   });
 
+  var getTerm = function() {
+    return me.val().slice(completeStart, completeEnd);
+  };
 
   $(this).keypress(function(e) {
+    var term, key = (e.char || String.fromCharCode(e.charCode));
 
-    if (!options.key) return;
+    // if we just started with an options.key, set start and end.
+    if (key === options.key && !autoCompleting()) {
+      completeStart = completeEnd = Discourse.Utilities.caretPosition(me[0]) + 1;
+    }
 
-    // keep hunting backwards till you hit a
-    if (e.which === options.key.charCodeAt(0)) {
-      var caretPosition = Discourse.Utilities.caretPosition(me[0]);
-      var prevChar = me.val().charAt(caretPosition - 1);
-      if (!prevChar || /\s/.test(prevChar)) {
-        completeStart = completeEnd = caretPosition;
+    if (!options.key) {
+      completeStart = 0;
+      completeEnd = Discourse.Utilities.caretPosition(me[0]);
+    }
+
+    if (autoCompleting()) {
+      if ((completeStart === completeEnd) && key === options.key) {
         updateAutoComplete(options.dataSource(""));
+      } else {
+        term = getTerm() + key;
+        completeEnd += 1;
+        updateAutoComplete(options.dataSource(term));
       }
+      return true;
     }
   });
 
   $(this).keydown(function(e) {
-    var c, caretPosition, i, initial, next, prev, prevIsGood, stopFound, term, total, userToComplete;
+    var caretPosition, i, term, total, userToComplete;
 
     if(options.allowAny){
       // saves us wiring up a change event as well, keypress is while its pressed
@@ -301,57 +301,38 @@ export default function(options) {
       },50);
     }
 
-    if (!options.key) {
-      completeStart = 0;
-    }
-    if (e.which === 16) return;
-    if ((completeStart === null) && e.which === 8 && options.key) {
-      c = Discourse.Utilities.caretPosition(me[0]);
-      next = me[0].value[c];
-      c -= 1;
-      initial = c;
-      prevIsGood = true;
-      while (prevIsGood && c >= 0) {
-        c -= 1;
-        prev = me[0].value[c];
-        stopFound = prev === options.key;
-        if (stopFound) {
-          prev = me[0].value[c - 1];
-          if (!prev || /\s/.test(prev)) {
-            completeStart = c;
-            caretPosition = completeEnd = initial;
-            term = me[0].value.substring(c + 1, initial);
-            updateAutoComplete(options.dataSource(term));
-            return true;
-          }
+    // Handle Backspacing into stuff
+    if ((!autoCompleting()) && e.which === Keys.BackSpace && options.key) {
+      var c = Discourse.Utilities.caretPosition(me[0]),
+          last, first,
+          text = me[0].value;
+      // search backwards until you find the last letter of the word
+      while (/[\s]/.test(text[c]) && c >= 0) { c--; }
+      last = c;
+      // search further until you find the first letter of the word
+      while (/[\S]/.test(text[c]) && c >= 0) { c--; }
+      first = c + 1;
+
+      if (text[first] === options.key) {
+        completeStart = first + 1;
+        completeEnd = (options.key === ":" ? last - 1 : last);
+
+        if (completeEnd >= completeStart) {
+          updateAutoComplete(options.dataSource(getTerm()));
         }
-        prevIsGood = /[a-zA-Z\.]/.test(prev);
+        return true;
       }
     }
 
-    // ESC
-    if (e.which === 27) {
-      if (completeStart !== null) {
-        closeAutocomplete();
-        return false;
-      }
-      return true;
-    }
-
-    if (completeStart !== null) {
-      caretPosition = Discourse.Utilities.caretPosition(me[0]);
-
-      // If we've backspaced past the beginning, cancel unless no key
-      if (caretPosition <= completeStart && options.key) {
-        closeAutocomplete();
-        return false;
-      }
-
+    if (autoCompleting()) {
       // Keyboard codes! So 80's.
       switch (e.which) {
-        case 13:
-        case 39:
-        case 9:
+        case Keys.Esc:
+          closeAutocomplete();
+          return false;
+        case Keys.Enter:
+        case Keys.RightArrow:
+        case Keys.Tab:
           if (!autocompleteOptions) return true;
           if (selectedOption >= 0 && (userToComplete = autocompleteOptions[selectedOption])) {
             completeTerm(userToComplete);
@@ -361,14 +342,14 @@ export default function(options) {
           }
           e.stopImmediatePropagation();
           return false;
-        case 38:
+        case Keys.UpArrow:
           selectedOption = selectedOption - 1;
           if (selectedOption < 0) {
             selectedOption = 0;
           }
           markSelected();
           return false;
-        case 40:
+        case Keys.DownArrow:
           total = autocompleteOptions.length;
           selectedOption = selectedOption + 1;
           if (selectedOption >= total) {
@@ -379,12 +360,11 @@ export default function(options) {
           }
           markSelected();
           return false;
-        default:
-          // otherwise they're typing - let's search for it!
+        case Keys.BackSpace:
+          caretPosition = Discourse.Utilities.caretPosition(me[0]) - 1;
           completeEnd = caretPosition;
-          if (e.which === 8) {
-            caretPosition--;
-          }
+
+
           if (caretPosition < 0) {
             closeAutocomplete();
             if (isInput) {
@@ -395,23 +375,17 @@ export default function(options) {
             }
             return false;
           }
-          term = me.val().substring(completeStart + (options.key ? 1 : 0), caretPosition);
-          if (e.which >= 48 && e.which <= 90) {
-            term += mapKeyPressToActualCharacter(e.shiftKey, e.which);
-          } else if (e.which === 187) {
-            term += "+";
-          } else if (e.which === 189) {
-            term += (e.shiftKey) ? "_" : "-";
-          } else if (e.which === 220) {
-            term += (e.shiftKey) ? "|" : "]";
-          } else if (e.which === 222) {
-            term += (e.shiftKey) ? "\"" : "'";
-          } else if (e.which !== 8) {
-            term += ",";
+
+          if (completeEnd < completeStart) {
+            closeAutocomplete();
+            return true;
           }
 
+          term = getTerm();
           updateAutoComplete(options.dataSource(term));
           return true;
+        default:
+          return true;
       }
     }
   });