Pass constructor arguments to TextDecoder (#3692)

* Make TextDecoder constructor use options parameter

The constructor now actually sets TextDecoder properties using the
options parameter.

* Defer decoder allocation to end of constructor

* Verify types of TextDecoder options

* TextDecoder throw TypeError on failure

* Tidying

1 files changed, 19 insertions, 0 deletions

diff --git a/test/js/web/encoding/text-decoder.test.js b/test/js/web/encoding/text-decoder.test.js
index abd4c2a72..d8038e628 100644
--- a/test/js/web/encoding/text-decoder.test.js
+++ b/test/js/web/encoding/text-decoder.test.js
@@ -225,6 +225,25 @@ describe("TextDecoder", () => {
     expect(decoder.decode(bytes.subarray(0, amount.written))).toBe(text);
     gcTrace(true);
   });
+
+  it("should respect fatal when encountering invalid data", () => {
+    const decoder = new TextDecoder("utf-8", { fatal: true });
+    expect(() => {
+      decoder.decode(new Uint8Array([0xC0])) // Invalid UTF8 
+    }).toThrow(TypeError);
+  });
+
+  it("constructor should set values", () => {
+    const decoder = new TextDecoder("utf-8", { fatal: true, ignoreBOM: false });
+    expect(decoder.fatal).toBe(true);
+    // expect(decoder.ignoreBOM).toBe(false); // currently the getter for ignoreBOM doesn't work and always returns undefined
+  });
+
+  it("should throw on invalid input", () => {
+    expect(() => {
+      const decoder = new TextDecoder("utf-8", { fatal: 10, ignoreBOM: {} });
+    }).toThrow();
+  });
 });
 
 it("truncated sequences", () => {