Google Chrome 49 removed the Viewport Helper, an indicator that shows the dimensions of the current window. Especially useful when developing a responsive website

Viewport Helper

(() => {
  const vpd = document.createElement('div'),
    st = {
      'position': 'fixed',
      'right': '0',
      'top': '0',
      'border': '5px solid #ccc',
      'background': '#ccc',
      'font-family': 'Arial',
      'font-size': '13px',
      'box-shadow': '0px 1px 2px',
      'z-index': '999999'
    },
    getD = () => {const {clientWidth, clientHeight} = document.documentElement; vpd.innerHTML = [clientWidth, clientHeight].map(c => c+'px').join(' × ')};

  for(var i in st) {
    vpd.style[i] = st[i]
  }
  getD();
  document.body.appendChild(vpd);
  window.addEventListener('resize', getD);

  let {left, right, top, bottom} = vpd.getBoundingClientRect();
  window.addEventListener('mousemove', ({clientX, clientY}) => {
    if (clientX > left && clientX < right && clientY > top && clientY < bottom) {
      vpd.style.top = 'auto';
      vpd.style.bottom = '0px';
    } else {
      vpd.style.top = '0px';
      vpd.style.bottom = 'auto';
    }
  })
})();

Great thanks man!
I use it every day and was unpleasantly surprised when after update I'm not find it again.
PS: I find that It's still showing in Opera (WebKit/Chromium versions). Nevertheless Chrome is my primary browser.