2 files changed, 20 insertions, 13 deletions
diff --git a/cli/js/tests/blob_test.ts b/cli/js/tests/blob_test.ts
index 57793af0e..b60877dd0 100644
--- a/cli/js/tests/blob_test.ts
+++ b/cli/js/tests/blob_test.ts
@@ -32,6 +32,14 @@ unitTest(function blobSlice(): void {
   assertEquals(b4.size, blob.size);
 });
 
+unitTest(function blobInvalidType(): void {
+  const blob = new Blob(["foo"], {
+    type: "\u0521",
+  });
+
+  assertEquals(blob.type, "");
+});
+
 unitTest(function blobShouldNotThrowError(): void {
   let hasThrown = false;
 
diff --git a/cli/js/web/blob.ts b/cli/js/web/blob.ts
index 5309ddaf4..c4e4674ab 100644
--- a/cli/js/web/blob.ts
+++ b/cli/js/web/blob.ts
@@ -139,24 +139,23 @@ export class DenoBlob implements domTypes.Blob {
     }
 
     const { ending = "transparent", type = "" } = options ?? {};
-    if (!containsOnlyASCII(type)) {
-      const errMsg = "The 'type' property must consist of ASCII characters.";
-      throw new SyntaxError(errMsg);
-    }
-
-    const bytes = processBlobParts(blobParts!, { ending, type });
     // Normalize options.type.
     let normalizedType = type;
-    if (type.length) {
-      for (let i = 0; i < type.length; ++i) {
-        const char = type[i];
-        if (char < "\u0020" || char > "\u007E") {
-          normalizedType = "";
-          break;
+    if (!containsOnlyASCII(type)) {
+      normalizedType = "";
+    } else {
+      if (type.length) {
+        for (let i = 0; i < type.length; ++i) {
+          const char = type[i];
+          if (char < "\u0020" || char > "\u007E") {
+            normalizedType = "";
+            break;
+          }
         }
+        normalizedType = type.toLowerCase();
       }
-      normalizedType = type.toLowerCase();
     }
+    const bytes = processBlobParts(blobParts!, { ending, type });
     // Set Blob object's properties.
     this[bytesSymbol] = bytes;
     this.size = bytes.byteLength;