Date-picker: fix week picker's value-format (#13754)

packages/date-picker/src/picker.vue

@@ -2,7 +2,7 @@
   <el-input
     class="el-date-editor"
     :class="'el-date-editor--' + type"
-    :readonly="!editable || readonly || type === 'dates'"
+    :readonly="!editable || readonly || type === 'dates' || type === 'week'"
     :disabled="pickerDisabled"
     :size="pickerSize"
     :name="name"
@@ -190,17 +190,9 @@ const TYPE_VALUE_RESOLVER_MAP = {
         : date.replace(/W/, week);
       return date;
     },
-    parser(text) {
-      const array = (text || '').split('w');
-      if (array.length === 2) {
-        const year = Number(array[0]);
-        const month = Number(array[1]);
-
-        if (!isNaN(year) && !isNaN(month) && month < 54) {
-          return text;
-        }
-      }
-      return null;
+    parser(text, format) {
+      // parse as if a normal date
+      return TYPE_VALUE_RESOLVER_MAP.date.parser(text, format);
     }
   },
   date: {