KERNEL-13846 refactor: 优化代码，采用解构方式引入变量

src/base/single/a/a.js

@@ -12,7 +12,7 @@ export class A extends BI.Text {
   static xtype = "bi.a";
   
   _defaultConfig() {
-    var conf = super._defaultConfig(arguments);
+    const conf = super._defaultConfig(arguments);
     return BI.extend(conf, {
         baseCls: (conf.baseCls || "") + " bi-a display-block",
         href: "",
@@ -23,11 +23,11 @@ export class A extends BI.Text {
   }
 
   render() {
-    var o = this.options;
+    const { href, target, el} = this.options;
     super.render();
-    this.element.attr({ href: o.href, target: o.target });
-    if (o.el) {
-        BI.createWidget(o.el, {
+    this.element.attr({ href, target });
+    if (el) {
+        BI.createWidget(el, {
             element: this,
         });
     }