Quelle  encodeInto.any.js

// META: global=window,worker
// META: script=/common/sab.js

[
  {
    "input": "Hi",
    "read": 0,
    "destinationLength": 0,
    "written": []
  },
  {
    "input": "A",
    "read": 1,
    "destinationLength": 10,
    "written": [0x41]
  },
  {
    "input": "\u{1D306}", // "\uD834\uDF06"
    "read": 2,
    "destinationLength": 4,
    "written": [0xF0, 0x9D, 0x8C, 0x86]
  },
  {
    "input": "\u{1D306}A",
    "read": 0,
    "destinationLength": 3,
    "written": []
  },
  {
    "input": "\uD834A\uDF06A¥Hi",
    "read": 5,
    "destinationLength": 10,
    "written": [0xEF, 0xBF, 0xBD, 0x41, 0xEF, 0xBF, 0xBD, 0x41, 0xC2, 0xA5]
  },
  {
    "input": "A\uDF06",
    "read": 2,
    "destinationLength": 4,
    "written": [0x41, 0xEF, 0xBF, 0xBD]
  },
  {
    "input": "¥¥",
    "read": 2,
    "destinationLength": 4,
    "written": [0xC2, 0xA5, 0xC2, 0xA5]
  }
].forEach(testData => {
  [
    {
      "bufferIncrease": 0,
      "destinationOffset": 0,
      "filler": 0
    },
    {
      "bufferIncrease": 10,
      "destinationOffset": 4,
      "filler": 0
    },
    {
      "bufferIncrease": 0,
      "destinationOffset": 0,
      "filler": 0x80
    },
    {
      "bufferIncrease": 10,
      "destinationOffset": 4,
      "filler": 0x80
    },
    {
      "bufferIncrease": 0,
      "destinationOffset": 0,
      "filler": "random"
    },
    {
      "bufferIncrease": 10,
      "destinationOffset": 4,
      "filler": "random"
    }
  ].forEach(destinationData => {
    ["ArrayBuffer", "SharedArrayBuffer"].forEach(arrayBufferOrSharedArrayBuffer => {
      test(() => {
        // Setup
        const bufferLength = testData.destinationLength + destinationData.bufferIncrease;
        const destinationOffset = destinationData.destinationOffset;
        const destinationLength = testData.destinationLength;
        const destinationFiller = destinationData.filler;
        const encoder = new TextEncoder();
        const buffer = createBuffer(arrayBufferOrSharedArrayBuffer, bufferLength);
        const view = new Uint8Array(buffer, destinationOffset, destinationLength);
        const fullView = new Uint8Array(buffer);
        const control = new Array(bufferLength);
        let byte = destinationFiller;
        for (let i = 0; i < bufferLength; i++) {
          if (destinationFiller === "random") {
            byte = Math.floor(Math.random() * 256);
          }
          control[i] = byte;
          fullView[i] = byte;
        }

        // It's happening
        const result = encoder.encodeInto(testData.input, view);

        // Basics
        assert_equals(view.byteLength, destinationLength);
        assert_equals(view.length, destinationLength);

        // Remainder
        assert_equals(result.read, testData.read);
        assert_equals(result.written, testData.written.length);
        for (let i = 0; i < bufferLength; i++) {
          if (i < destinationOffset || i >= (destinationOffset + testData.written.length)) {
            assert_equals(fullView[i], control[i]);
          } else {
            assert_equals(fullView[i], testData.written[i - destinationOffset]);
          }
        }
      }, "encodeInto() into "  + arrayBufferOrSharedArrayBuffer + " with " + testData.input + " and destination length " + testData.destinationLength + ", offset " + destinationData.destinationOffset + ", filler " + destinationData.filler);
    })
  });
});

["DataView",
 "Int8Array",
 "Int16Array",
 "Int32Array",
 "Uint16Array",
 "Uint32Array",
 "Uint8ClampedArray",
 "BigInt64Array",
 "BigUint64Array",
 "Float16Array",
 "Float32Array",
 "Float64Array"].forEach(type => {
  ["ArrayBuffer", "SharedArrayBuffer"].forEach((arrayBufferOrSharedArrayBuffer) => {
    test(() => {
      const viewInstance = new self[type](createBuffer(arrayBufferOrSharedArrayBuffer, 0));
      assert_throws_js(TypeError, () => new TextEncoder().encodeInto("", viewInstance));
    }, "Invalid encodeInto() destination: " + type + ", backed by: " + arrayBufferOrSharedArrayBuffer);
  });
});

["ArrayBuffer", "SharedArrayBuffer"].forEach((arrayBufferOrSharedArrayBuffer) => {
  test(() => {
    assert_throws_js(TypeError, () => new TextEncoder().encodeInto("", createBuffer(arrayBufferOrSharedArrayBuffer, 10)));
  }, "Invalid encodeInto() destination: " + arrayBufferOrSharedArrayBuffer);
});

test(() => {
  const buffer = new ArrayBuffer(10),
        view = new Uint8Array(buffer);
  let { read, written } = new TextEncoder().encodeInto("", view);
  assert_equals(read, 0);
  assert_equals(written, 0);
  new MessageChannel().port1.postMessage(buffer, [buffer]);
  ({ read, written } = new TextEncoder().encodeInto("", view));
  assert_equals(read, 0);
  assert_equals(written, 0);
  ({ read, written } = new TextEncoder().encodeInto("test", view));
  assert_equals(read, 0);
  assert_equals(written, 0);
}, "encodeInto() and a detached output buffer");