test/mjsunit/compiler/null-compare.js

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function IsNull(x) {
  if (x == null) return true; else return false;
}

assertTrue(IsNull(null), "null == null");
assertTrue(IsNull(void 0), "void 0 == null");
assertFalse(IsNull(42), "42 != null");


function IsNullStrict(x) {
  if (x === null) return true; else return false;
}

assertTrue(IsNullStrict(null), "null === null");
assertFalse(IsNullStrict(void 0), "void 0 != null");
assertFalse(IsNullStrict(87), "87 !== null");


function GimmeFalse(x) {
  if ((x & 1) == null) return true;
  if ((x | 3) === null) return true;
  return false;
}

assertFalse(GimmeFalse(1), "GimmeFalse(1)");
assertFalse(GimmeFalse(null), "GimmeFalse(null)");
assertFalse(GimmeFalse({}), "GimmeFalse({})");