refactor(typescript-estree): simplify applyModifiersToResult (#3084)

packages/typescript-estree/src/convert.ts

@@ -580,13 +580,13 @@ export class Converter {
     if (!modifiers || !modifiers.length) {
       return;
     }
+    const remainingModifiers: TSESTree.Modifier[] = [];
     /**
      * Some modifiers are explicitly handled by applying them as
      * boolean values on the result node. As well as adding them
      * to the result, we remove them from the array, so that they
      * are not handled twice.
      */
-    const handledModifierIndices: { [key: number]: boolean } = {};
     for (let i = 0; i < modifiers.length; i++) {
       const modifier = modifiers[i];
       switch (modifier.kind) {
@@ -596,31 +596,26 @@ export class Converter {
          */
         case SyntaxKind.ExportKeyword:
         case SyntaxKind.DefaultKeyword:
-          handledModifierIndices[i] = true;
           break;
         case SyntaxKind.ConstKeyword:
           (result as any).const = true;
-          handledModifierIndices[i] = true;
           break;
         case SyntaxKind.DeclareKeyword:
           result.declare = true;
-          handledModifierIndices[i] = true;
           break;
         default:
+          remainingModifiers.push(this.convertChild(modifier));
+          break;
       }
     }
     /**
      * If there are still valid modifiers available which have
      * not been explicitly handled above, we just convert and
      * add the modifiers array to the result node.
      */
-    const remainingModifiers = modifiers.filter(
-      (_, i) => !handledModifierIndices[i],
-    );
-    if (!remainingModifiers || !remainingModifiers.length) {
-      return;
+    if (remainingModifiers.length) {
+      result.modifiers = remainingModifiers;
     }
-    result.modifiers = remainingModifiers.map(el => this.convertChild(el));
   }
 
   /**