Preventing move of "use strict"; directive during obfuscation

src/node/NodeGuards.ts

@@ -422,15 +422,6 @@ export class NodeGuards {
         return node.type === NodeType.UnaryExpression;
     }
 
-    /**
-     * @param {Node} node
-     * @returns {boolean}
-     */
-    public static isUseStrictOperator (node: ESTree.Node): node is ESTree.Directive {
-        return NodeGuards.isDirectiveNode(node)
-            && node.directive === 'use strict';
-    }
-
     /**
      * @param {Node} node
      * @returns {boolean}

src/node/NodeMetadata.ts

@@ -1,4 +1,5 @@
 import * as ESTree from 'estree';
+import { TNodeWithLexicalScope } from '../types/node/TNodeWithLexicalScope';
 
 export class NodeMetadata {
     /**
@@ -14,7 +15,10 @@ export class NodeMetadata {
      * @param {keyof T} metadataKey
      * @returns {T[keyof T] | undefined}
      */
-    public static get <T extends ESTree.BaseNodeMetadata> (node: ESTree.Node, metadataKey: keyof T): T[keyof T] | undefined {
+    public static get <
+        T extends ESTree.BaseNodeMetadata,
+        TMetadataKey extends keyof T
+    > (node: ESTree.Node, metadataKey: TMetadataKey): T[TMetadataKey] | undefined {
         return node.metadata !== undefined
             ? (<T>node.metadata)[metadataKey]
             : undefined;
@@ -25,7 +29,7 @@ export class NodeMetadata {
      * @returns {boolean}
      */
     public static isForceTransformNode (node: ESTree.Node): boolean {
-        return NodeMetadata.get(node, 'forceTransformNode') === true;
+        return NodeMetadata.get<ESTree.BaseNodeMetadata, 'forceTransformNode'>(node, 'forceTransformNode') === true;
     }
 
     /**
@@ -33,7 +37,7 @@ export class NodeMetadata {
      * @returns {boolean}
      */
     public static isIgnoredNode (node: ESTree.Node): boolean {
-        return NodeMetadata.get(node, 'ignoredNode') === true;
+        return NodeMetadata.get<ESTree.BaseNodeMetadata, 'ignoredNode'>(node, 'ignoredNode') === true;
     }
 
     /**
@@ -41,6 +45,18 @@ export class NodeMetadata {
      * @returns {boolean}
      */
     public static isReplacedLiteral (literalNode: ESTree.Literal): boolean {
-        return NodeMetadata.get<ESTree.LiteralNodeMetadata>(literalNode, 'replacedLiteral') === true;
+        return NodeMetadata.get<ESTree.LiteralNodeMetadata, 'replacedLiteral'>(literalNode, 'replacedLiteral') === true;
+    }
+
+    /**
+     * @param {TNodeWithLexicalScope} nodeWithLexicalScope
+     * @returns {Directive | null | undefined}
+     */
+    public static getDirectiveNode (nodeWithLexicalScope: TNodeWithLexicalScope): ESTree.Directive | null | undefined {
+        return NodeMetadata.get<
+            ESTree.ProgramNodeMetadata
+            | ESTree.FunctionNodeMetadata,
+            'directiveNode'
+        >(nodeWithLexicalScope, 'directiveNode');
     }
 }