inputPlaceholder not working

[Innarticles]

I have this piece of code:

swal({
      imageUrl: "/image.png",
      imageSize: "279x60",
      inputPlaceholder: "Enter your email to get invited",
      title: "<h3>Title text here?</h3>",
      text: "Text here.",
      type: "input",
      html: true,
      showCancelButton: true,
      closeOnConfirm: false,
      animation: "slide-from-top"
    }

But the input placeholder is not showing. Any help here?