Cascader: remove unnecessary DOM operation (#14788)

* Cascader: remove unnecessary DOM operation

* update cascader test

packages/cascader/src/main.vue

@@ -239,10 +239,6 @@ export default {
     currentValue(value) {
       this.dispatch('ElFormItem', 'el.form.change', [value]);
     },
-    currentLabels(value) {
-      const inputLabel = this.showAllLevels ? value.join('/') : value[value.length - 1] ;
-      this.$refs.input.$refs.input.setAttribute('value', inputLabel);
-    },
     options: {
       deep: true,
       handler(value) {

test/unit/specs/cascader.spec.js

@@ -82,6 +82,7 @@ describe('Cascader', () => {
             expect(vm.selectedOptions[0]).to.be.equal('zhejiang');
             expect(vm.selectedOptions[1]).to.be.equal('hangzhou');
             expect(vm.selectedOptions[2]).to.be.equal('xihu');
+            expect(vm.$refs.cascader.$el.querySelector('.el-input__inner').value).to.be.equal('');
 
             triggerEvent(vm.$refs.cascader.$el, 'mouseenter');
             vm.$nextTick(_ => {