[improvement] optimize popup mixin (#1979)

packages/mixins/popup/context.js

@@ -1,13 +1,8 @@
 export default {
-  id: 1,
   zIndex: 2000,
   stack: [],
   lockCount: 0,
 
-  plusKey(key) {
-    return this[key]++;
-  },
-
   get top() {
     return this.stack[this.stack.length - 1];
   }

packages/mixins/popup/index.js

@@ -61,10 +61,6 @@ export default {
     }
   },
 
-  created() {
-    this._popupId = 'popup-' + context.plusKey('id');
-  },
-
   mounted() {
     if (this.getContainer) {
       this.move();
@@ -101,7 +97,7 @@ export default {
         return;
       }
 
-      // 如果属性中传入了`zIndex`，则覆盖`context`中对应的`zIndex`
+      // cover default zIndex
       if (this.zIndex !== undefined) {
         context.zIndex = this.zIndex;
       }
@@ -112,6 +108,7 @@ export default {
       if (this.lockScroll) {
         on(document, 'touchstart', this.touchStart);
         on(document, 'touchmove', this.onTouchMove);
+
         if (!context.lockCount) {
           document.body.classList.add('van-overflow-hidden');
         }
@@ -128,13 +125,14 @@ export default {
         context.lockCount--;
         off(document, 'touchstart', this.touchStart);
         off(document, 'touchmove', this.onTouchMove);
+
         if (!context.lockCount) {
           document.body.classList.remove('van-overflow-hidden');
         }
       }
 
       this.opened = false;
-      manager.close(this._popupId);
+      manager.close(this);
       this.$emit('input', false);
     },
 
@@ -184,16 +182,16 @@ export default {
     renderOverlay() {
       if (this.overlay) {
         manager.open(this, {
-          zIndex: context.plusKey('zIndex'),
+          zIndex: context.zIndex++,
           className: this.overlayClass,
           customStyle: this.overlayStyle
         });
       } else {
-        manager.close(this._popupId);
+        manager.close(this);
       }
 
       this.$nextTick(() => {
-        this.$el.style.zIndex = context.plusKey('zIndex');
+        this.$el.style.zIndex = context.zIndex++;
       });
     }
   }

packages/mixins/popup/manager.js

@@ -10,23 +10,23 @@ const defaultConfig = {
 export default {
   open(vm, config) {
     /* istanbul ignore next */
-    if (!context.stack.some(item => item.vm._popupId === vm._popupId)) {
+    if (!context.stack.some(item => item.vm === vm)) {
       const el = vm.$el;
-      const targetNode = el && el.parentNode && el.parentNode.nodeType !== 11 ? el.parentNode : document.body;
-      context.stack.push({ vm, config, targetNode });
+      const target = el && el.parentNode ? el.parentNode : document.body;
+      context.stack.push({ vm, config, target });
       this.update();
     };
   },
 
-  close(id) {
+  close(vm) {
     const { stack } = context;
 
     if (stack.length) {
-      if (context.top.vm._popupId === id) {
+      if (context.top.vm === vm) {
         stack.pop();
         this.update();
       } else {
-        context.stack = stack.filter(item => item.vm._popupId !== id);
+        context.stack = stack.filter(item => item.vm !== vm);
       }
     }
   },
@@ -48,9 +48,9 @@ export default {
     }
 
     if (context.top) {
-      const { targetNode, config } = context.top;
+      const { target, config } = context.top;
 
-      targetNode.appendChild(modal.$el);
+      target.appendChild(modal.$el);
       Object.assign(modal, {
         ...defaultConfig,
         ...config,