isDataView

Determines whether a value is a DataView with enhanced type safety. Provides reliable DataView detection using instanceof check for identifying binary data view objects used for reading and writing binary data in ArrayBuffers with specific endianness control.

Signature

const isDataView: (value: unknown) => value is DataView

Parameters

Name	Type	Description
value	-	Value to test for DataView type

Returns

Type-safe boolean indicating whether the value is a DataView

Examples

Basic DataView detection

import { isDataView } from '@winglet/common-utils';

const buffer = new ArrayBuffer(16);
const dataView = new DataView(buffer);
const uint8Array = new Uint8Array(buffer);

console.log(isDataView(dataView)); // true
console.log(isDataView(buffer)); // false (ArrayBuffer, not DataView)
console.log(isDataView(uint8Array)); // false (TypedArray, not DataView)
console.log(isDataView({})); // false
console.log(isDataView(null)); // false

Binary data processing with DataView

function processBinaryData(data: unknown) {
  if (isDataView(data)) {
    // TypeScript knows data is DataView
    console.log(`DataView with ${data.byteLength} bytes`);

    // Safe to use DataView methods
    if (data.byteLength >= 4) {
      const int32Value = data.getInt32(0, true); // little-endian
      const float32Value = data.getFloat32(0, false); // big-endian

      return { int32Value, float32Value };
    }
  }

  throw new Error('Expected DataView for binary data processing');
}

Multi-format binary reader

function readBinaryHeader(view: unknown) {
  if (!isDataView(view)) {
    throw new Error('Binary header requires DataView');
  }

  // Read various data types with endianness control
  return {
    magic: view.getUint32(0, true),        // 4 bytes, little-endian
    version: view.getUint16(4, true),     // 2 bytes, little-endian
    flags: view.getUint8(6),              // 1 byte
    timestamp: view.getBigUint64(8, true), // 8 bytes, little-endian
    checksum: view.getUint32(16, false)   // 4 bytes, big-endian
  };
}

File format validation

async function validateBinaryFile(file: File) {
  const buffer = await file.arrayBuffer();
  const view = new DataView(buffer);

  if (isDataView(view)) {
    // Check file signature
    const signature = view.getUint32(0, false);

    switch (signature) {
      case 0x89504E47: // PNG
        return 'PNG image';
      case 0x47494638: // GIF
        return 'GIF image';
      case 0xFFD8FFE0: // JPEG
        return 'JPEG image';
      default:
        return 'Unknown format';
    }
  }

  return 'Invalid binary data';
}

Network protocol parsing

interface PacketHeader {
  type: number;
  length: number;
  sequenceId: number;
  checksum: number;
}

function parsePacketHeader(data: unknown): PacketHeader | null {
  if (!isDataView(data) || data.byteLength < 10) {
    return null;
  }

  return {
    type: data.getUint8(0),
    length: data.getUint16(1, true),
    sequenceId: data.getUint32(3, true),
    checksum: data.getUint16(7, true)
  };
}

Playground

import { isDataView } from '@winglet/common-utils';

const buffer = new ArrayBuffer(16);
const dataView = new DataView(buffer);
const uint8Array = new Uint8Array(buffer);

console.log(isDataView(dataView)); // true
console.log(isDataView(buffer)); // false (ArrayBuffer, not DataView)
console.log(isDataView(uint8Array)); // false (TypedArray, not DataView)
console.log(isDataView({})); // false
console.log(isDataView(null)); // false

Notes

Key Features:

• Provides endianness control (little/big endian)
• Supports all numeric types (Int8, Uint16, Float32, BigInt64, etc.)
• Allows unaligned memory access
• Works with any offset within the underlying ArrayBuffer

Use Cases:

• Binary file format parsing
• Network protocol implementation
• Low-level data manipulation
• Cross-platform binary data exchange
• Endianness-sensitive operations

Related Types:

• Use isArrayBuffer() for the underlying buffer
• Use isTypedArray() for typed array views
• Use isBuffer() for Node.js Buffer objects

Performance: Direct instanceof check provides optimal performance.