object.ts

// Object.is

assert(Object.is(+0.0, +0.0) == true);
assert(Object.is(+0.0, -0.0) == false);
assert(Object.is(-0.0, +0.0) == false);
assert(Object.is(+0.0, +1.0) == false);
assert(Object.is(+1.0, -1.0) == false);
assert(Object.is(+1.0, +1.0) == true);

assert(Object.is(+Infinity, +Infinity) == true);
assert(Object.is(-Infinity, -Infinity) == true);
assert(Object.is(+Infinity, -Infinity) == false);
assert(Object.is(-Infinity, +Infinity) == false);
assert(Object.is(+Infinity, NaN) == false);
assert(Object.is(NaN, Infinity) == false);
assert(Object.is(NaN, NaN) == true);

assert(Object.is<f32>(+0.0, +0.0) == true);
assert(Object.is<f32>(+0.0, -0.0) == false);
assert(Object.is<f32>(-0.0, +0.0) == false);
assert(Object.is<f32>(+0.0, +1.0) == false);
assert(Object.is<f32>(+1.0, -1.0) == false);
assert(Object.is<f32>(+1.0, +1.0) == true);

assert(Object.is<f32>(+Infinity, +Infinity) == true);
assert(Object.is<f32>(-Infinity, -Infinity) == true);
assert(Object.is<f32>(+Infinity, -Infinity) == false);
assert(Object.is<f32>(-Infinity, +Infinity) == false);
assert(Object.is<f32>(+Infinity, NaN) == false);
assert(Object.is<f32>(NaN, Infinity) == false);
assert(Object.is<f32>(NaN, NaN) == true);

assert(Object.is(-0.0, 1e-1 * (-1e-308)) == false);
assert(Object.is(0, 0.0) == true);

assert(Object.is<i32>(+0, -0) == true);
assert(Object.is<i32>(+1, -1) == false);

assert(Object.is(true, true) == true);
assert(Object.is(true, false) == false);
assert(Object.is(false, false) == true);

assert(Object.is("a", "a") == true);
assert(Object.is("a", "b") == false);
assert(Object.is("a", "ab") == false);

assert(Object.is<string | null>(null, null) == true);
assert(Object.is<string | null>("", null) == false);
assert(Object.is<string | null>(null, "") == false);

// Implicit and explicit inheritance

class Implicit {
  constructor() {
    // no super()
  }
}
class Explicit extends Object {
  constructor() {
    super();
  }
}
{
  let implicit = new Implicit();
  assert(implicit instanceof Object);
  assert(!isDefined(Implicit.is)); // does not inherit static members

  let explicit = new Explicit();
  assert(explicit instanceof Object);
  assert(isDefined(Explicit.is)); // does inherit static members

  let object: Object = explicit;
  assert(object instanceof Explicit); // dynamic check

  assert((<Object>implicit) instanceof Implicit);
  assert((<Object>explicit) instanceof Explicit);
}