How to make fixed-content go above iOS keyboard?

Question

I can only find questions where people have the opposite problem.

I want my fixed content to go above the iOS keyboard. Image of the problem:

I want iOS to behave like Android.

Is there a simple way to achieve this?

Parent element css:

.parent{
    position:fixed;
    top: 0;
    left 0;
    right: 0;
    bottom: 0;
    width: 100%;
    height: 100%;
}

Button css:

.button{
    position:fixed;
    left 0;
    right: 0;
    bottom: 0;
    width: 100%;
    height: 5rem;
}

Answer 1

We can use VisualViewport to calculate keyboard height. So we can set fixed-content pos correct.

Small demo: https://whatwg6.github.io/pos-above-keyboard/index.html

Github Repo: https://github.com/whatwg6/pos-above-keyboard

Code snippet:

  const button = document.getElementById("button");
  const input = document.getElementById("input");
  let height = window.visualViewport.height;
  const viewport = window.visualViewport;

  window.addEventListener("scroll", inputBlur);
  window.visualViewport.addEventListener("resize", resizeHandler);

  function inputBlur() {
    input.blur();
  }

  function resizeHandler() {
    if (!/iPhone|iPad|iPod/.test(window.navigator.userAgent)) {
      height = viewport.height;
    }
    button.style.bottom = `${height - viewport.height + 10}px`;
  }

  function blurHandler() {
    button.style.bottom = "10px";
  }

  html,
  body {
    margin: 0;
    padding: 0;
  }

  #button {
    position: fixed;
    width: 100%;
    bottom: 10px;
    background-color: rebeccapurple;
    line-height: 40px;
    text-align: center;
  }

<input
  type="text"
  inputmode="decimal"
  value="0.99"
  id="input"
  onblur="blurHandler()"
/>
<div id="button" onclick="inputBlur()">Button</div>

Problems: https://developers.google.com/web/updates/2017/09/visual-viewport-api#the_event_rate_is_slow

Why not innerHeight?: Iphone safari not resizing viewport on keyboard open