Dev: Add $0 reference

src/Console/Log.es6

@@ -305,7 +305,7 @@ function transMsg(msg)
         msg = 'Object ' + JSON.stringify(msg);
     }
 
-    return util.escape(msg);
+    return util.escape(util.toStr(msg));
 }
 
 function transMultipleMsg(args)
@@ -328,6 +328,5 @@ function transCode(code)
 function txtToHtml(str)
 {
     return str.replace(/\n/g, '<br/>')
-              .replace(/\t/g, '&nbsp;&nbsp;&nbsp;&nbsp;')
-              .replace(/ /g, '&nbsp;&nbsp;');
+              .replace(/\t/g, '&nbsp;&nbsp;&nbsp;&nbsp;');
 }

src/Elements/Elements.es6

@@ -93,6 +93,7 @@ export default class Elements extends Tool
         this._curCssStore = new CssStore(el);
         this._highlight.setEl(el);
         this._rmDefComputedStyle = true;
+        window.$0 = el;
 
         this._render();
     }

src/lib/util.js

@@ -2380,6 +2380,33 @@ module.exports = (function ()
         return exports;
     })({});
 
+    /* ------------------------------ toStr ------------------------------ */
+
+    var toStr = _.toStr = (function (exports)
+    {
+        /* Convert value to a string.
+         *
+         * |Name  |Type  |Desc            |
+         * |------------------------------|
+         * |val   |*     |Value to convert|
+         * |return|string|Resulted string |
+         *
+         * ```javascript
+         * toStr(null); // -> ''
+         * toStr(1); // -> '1'
+         * toStr(false); // -> 'false'
+         * toStr([1, 2, 3]); // -> '1,2,3'
+         * ```
+         */
+
+        function exports(val)
+        {
+            return val == null ? '' : val.toString();
+        }
+
+        return exports;
+    })({});
+
     /* ------------------------------ trim ------------------------------ */
 
     var trim = _.trim = (function (exports)