legacyNoObservedAttributes: Ensure user created runs before attributesChanged

Author: Steven Orvell

lib/legacy/legacy-element-mixin.js

@@ -122,16 +122,7 @@ export const LegacyElementMixin = dedupingMixin((base) => {
      * @override
      * @return {void}
      */
-    created() {
-      // Pull all attribute values 1x if `legacyNoObservedAttributes` is set.
-      if (legacyNoObservedAttributes && this.hasAttributes()) {
-        const a = this.attributes;
-        for (let i=0, l=a.length; i < l; i++) {
-          const attr = a[i];
-          this.__attributeReaction(attr.name, null, attr.value);
-        }
-      }
-    }
+    created() {}
 
     /**
      * Processes an attribute reaction when the `legacyNoObservedAttributes`
@@ -310,6 +301,14 @@ export const LegacyElementMixin = dedupingMixin((base) => {
         super._initializeProperties();
         this.root = /** @type {HTMLElement} */(this);
         this.created();
+        // Pull all attribute values 1x if `legacyNoObservedAttributes` is set.
+        if (legacyNoObservedAttributes && this.hasAttributes()) {
+          const a = this.attributes;
+          for (let i=0, l=a.length; i < l; i++) {
+            const attr = a[i];
+            this.__attributeReaction(attr.name, null, attr.value);
+          }
+        }
         // Ensure listeners are applied immediately so that they are
         // added before declarative event listeners. This allows an element to
         // decorate itself via an event prior to any declarative listeners

test/unit/legacy-noattributes.html

@@ -66,7 +66,11 @@
           camelCase: String,
           disabled: {type: Boolean, value: 'true'}
         },
+        created() {
+          this.wasCreated = true;
+        },
         attributeChanged(name, old, value) {
+          this.wasCreatedInAttributeChanged = this.wasCreated;
           this.attrInfo = {name, old, value};
         }
       });
@@ -104,6 +108,10 @@
         assert.equal(el.camelCase, 'camelCase');
       });
 
+      test('created called before attributeChanged', () => {
+        assert.isTrue(el.wasCreatedInAttributeChanged);
+      });
+
       test('attributeChanged gets expected arguments', () => {
         el = fixture('one-attr');
         assert.deepEqual(el.attrInfo, {name: 'foo', old: null, value: 'foo'});