Testing Distinct NaN Representations in JavaScript

test-nan.js

  var a = new Float64Array(2);
  var aBytes = new Uint8Array(a.buffer);

  aBytes[6] = 248;
  aBytes[7] = 255;
  aBytes[14] = 248;
  aBytes[15] = 127;

  var nan1 = a[0];
  var nan2 = a[1];

  assert(isNaN(nan1), 'first NaN representation');
  assert(isNaN(nan2), 'second NaN representation');

  var b = new Float64Array(2);
  var bBytes = new Uint8Array(b.buffer);

  b[0] = nan2;
  b[1] = nan1;

  print('aBytes:', aBytes.join(' '));
  print('bBytes:', bBytes.join(' '));

  assert.sameValue(bBytes[6], 248);
  assert.sameValue(bBytes[7], 127);
  assert.sameValue(bBytes[14], 248);
  assert.sameValue(bBytes[15], 255);