Buffer to ArrayBuffer

index.js

const {readFile} = require('fs');

readFile('path/to/some/file', (error, buffer) => {
  const arrayBuffer = new ArrayBuffer(buffer.length)
  const bufferView = new Uint8Array(arrayBuffer);

  for (var i=0, length=buffer.length; i < length; i++) {
    bufferView[i] = buffer[i];
  }
  
  console.log(buffer, arrayBuffer);
});