typescript-eslint · nayounsang · Jun 28, 2025 · Jun 28, 2025 · Jun 28, 2025 · Jun 28, 2025
diff --git a/.../src/legacy-fixtures/types/fixtures/template-literal-type-1/snapshots/1-TSESTree-AST.shot b/.../src/legacy-fixtures/types/fixtures/template-literal-type-1/snapshots/1-TSESTree-AST.shot
diff --git a/...legacy-fixtures/types/fixtures/template-literal-type-1/snapshots/5-AST-Alignment-AST.shot b/...legacy-fixtures/types/fixtures/template-literal-type-1/snapshots/5-AST-Alignment-AST.shot
diff --git a/.../src/legacy-fixtures/types/fixtures/template-literal-type-2/snapshots/1-TSESTree-AST.shot b/.../src/legacy-fixtures/types/fixtures/template-literal-type-2/snapshots/1-TSESTree-AST.shot
diff --git a/...legacy-fixtures/types/fixtures/template-literal-type-2/snapshots/5-AST-Alignment-AST.shot b/...legacy-fixtures/types/fixtures/template-literal-type-2/snapshots/5-AST-Alignment-AST.shot
diff --git a/.../src/legacy-fixtures/types/fixtures/template-literal-type-3/snapshots/1-TSESTree-AST.shot b/.../src/legacy-fixtures/types/fixtures/template-literal-type-3/snapshots/1-TSESTree-AST.shot
diff --git a/...legacy-fixtures/types/fixtures/template-literal-type-3/snapshots/5-AST-Alignment-AST.shot b/...legacy-fixtures/types/fixtures/template-literal-type-3/snapshots/5-AST-Alignment-AST.shot
diff --git a/.../src/legacy-fixtures/types/fixtures/template-literal-type-4/snapshots/1-TSESTree-AST.shot b/.../src/legacy-fixtures/types/fixtures/template-literal-type-4/snapshots/1-TSESTree-AST.shot
diff --git a/...legacy-fixtures/types/fixtures/template-literal-type-4/snapshots/5-AST-Alignment-AST.shot b/...legacy-fixtures/types/fixtures/template-literal-type-4/snapshots/5-AST-Alignment-AST.shot
diff --git a/packages/ast-spec/src/special/TemplateElement/spec.ts b/packages/ast-spec/src/special/TemplateElement/spec.ts
@@ -5,7 +5,7 @@ export interface TemplateElement extends BaseNode {
   type: AST_NODE_TYPES.TemplateElement;
   tail: boolean;
   value: {
-    cooked: string;
+    cooked: string | null;
     raw: string;
   };
 }
diff --git a/packages/ast-spec/tests/fixtures-with-differences-ast.shot b/packages/ast-spec/tests/fixtures-with-differences-ast.shot
diff --git a/packages/typescript-estree/src/convert.ts b/packages/typescript-estree/src/convert.ts
@@ -90,6 +90,7 @@ function isEntityNameExpression(
 }
 
 export class Converter {
+  #isInTaggedTemplate = false;
   private allowPattern = false;
   private readonly ast: ts.SourceFile;
   private readonly esTreeNodeToTSNodeMap = new WeakMap();
@@ -401,6 +402,38 @@ export class Converter {
     }
   }
 
+  #isValidEscape(arg: string): boolean {
+    const unicode = /\\u([0-9a-fA-F]{4})/g;
+    const unicodeBracket = /\\u\{([0-9a-fA-F]+)\}/g; // supports ES6+
+    const hex = /\\x([0-9a-fA-F]{2})/g;
+    const validShort = /\\[nrtbfv0\\'"]/g;
+
+    const allEscapes =
+      /\\(u\{[^}]*\}|u[0-9a-fA-F]{0,4}|x[0-9a-fA-F]{0,2}|[^ux])/g;
+
+    let match: RegExpExecArray | null;
+    while ((match = allEscapes.exec(arg)) != null) {
+      const escape = match[0];
+
+      if (
+        unicode.test(escape) ||
+        (unicodeBracket.test(escape) &&
+          (() => {
+            const cp = parseInt(escape.match(unicodeBracket)![1], 16);
+            return cp <= 0x10ffff;
+          })()) ||
+        hex.test(escape) ||
+        validShort.test(escape)
+      ) {
+        continue;
+      }
+
+      return false;
+    }
+
+    return true;
+  }
+
   #throwError(node: number | ts.Node, message: string): asserts node is never {
     let start;
     let end;
@@ -1889,7 +1922,10 @@ export class Converter {
               type: AST_NODE_TYPES.TemplateElement,
               tail: true,
               value: {
-                cooked: node.text,
+                cooked:
+                  this.#isValidEscape(node.text) && this.#isInTaggedTemplate
+                    ? node.text
+                    : null,
                 raw: this.ast.text.slice(
                   node.getStart(this.ast) + 1,
                   node.end - 1,
@@ -1917,19 +1953,25 @@ export class Converter {
         return result;
       }
 
-      case SyntaxKind.TaggedTemplateExpression:
-        return this.createNode<TSESTree.TaggedTemplateExpression>(node, {
-          type: AST_NODE_TYPES.TaggedTemplateExpression,
-          quasi: this.convertChild(node.template),
-          tag: this.convertChild(node.tag),
-          typeArguments:
-            node.typeArguments &&
-            this.convertTypeArgumentsToTypeParameterInstantiation(
-              node.typeArguments,
-              node,
-            ),
-        });
-
+      case SyntaxKind.TaggedTemplateExpression: {
+        this.#isInTaggedTemplate = true;
+        const result = this.createNode<TSESTree.TaggedTemplateExpression>(
+          node,
+          {
+            type: AST_NODE_TYPES.TaggedTemplateExpression,
+            quasi: this.convertChild(node.template),
+            tag: this.convertChild(node.tag),
+            typeArguments:
+              node.typeArguments &&
+              this.convertTypeArgumentsToTypeParameterInstantiation(
+                node.typeArguments,
+                node,
+              ),
+          },
+        );
+        this.#isInTaggedTemplate = false;
+        return result;
+      }
       case SyntaxKind.TemplateHead:
       case SyntaxKind.TemplateMiddle:
       case SyntaxKind.TemplateTail: {
@@ -1938,7 +1980,10 @@ export class Converter {
           type: AST_NODE_TYPES.TemplateElement,
           tail,
           value: {
-            cooked: node.text,
+            cooked:
+              this.#isValidEscape(node.text) && this.#isInTaggedTemplate
+                ? node.text
+                : null,
             raw: this.ast.text.slice(
               node.getStart(this.ast) + 1,
               node.end - (tail ? 1 : 2),