Avoid to use delete operator

sosukesuzuki · sosukesuzuki · commit d5077ffbfa39 · 2021-08-16T10:50:42.000+09:00
diff --git a/packages/babel-parser/src/plugins/typescript/index.js b/packages/babel-parser/src/plugins/typescript/index.js
@@ -2379,6 +2379,8 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       member: any,
       state: N.ParseClassMemberState,
     ): void {
+      const modified = {};
+
       const invalidModifersForStaticBlocks = [
         "declare",
         "private",
@@ -2389,20 +2391,32 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         "readonly",
       ];
       this.tsParseModifiers(
-        member,
+        modified,
         invalidModifersForStaticBlocks.concat(["static"]),
       );
 
+      for (const modifier of Object.keys(modified)) {
+        if (modifier === "accessibility") {
+          member.accessibility = modified[modifier];
+        } else if (modifier !== "static") {
+          member[modifier] = true;
+        }
+      }
+
       const callParseClassMemberWithIsStatic = () => {
-        const isStatic = !!member.static;
-        if (isStatic && this.eat(tt.braceL)) {
-          delete member.static;
+        if (modified.static && this.eat(tt.braceL)) {
           if (this.tsHasSomeModifiers(member, invalidModifersForStaticBlocks)) {
             this.raise(this.state.pos, TSErrors.StaticBlockCannotHaveModifier);
           }
           this.parseClassStaticBlock(classBody, ((member: any): N.StaticBlock));
         } else {
-          this.parseClassMemberWithIsStatic(classBody, member, state, isStatic);
+          member.static = modified.static;
+          this.parseClassMemberWithIsStatic(
+            classBody,
+            member,
+            state,
+            !!member.static,
+          );
         }
       };
       if (member.declare) {
