Cacher is the code snippet organizer for pro developers

// get browser width and height on window resize
var headerEl = document.getElementById('header');
// when window size changed - resize first block
window.addEventListener('resize', setWindowSize);

function setWindowSize() {
  if (typeof(window.innerWidth) == 'number') {
    myWidth = window.innerWidth;
    myHeight = window.innerHeight;
    setheight(myHeight);
  } else {
    if (document.documentElement && (document.documentElement.clientWidth || document.documentElement.clientHeight)) {
      myWidth = document.documentElement.clientWidth;
      myHeight = document.documentElement.clientHeight;
      setheight(myHeight);
    } else {
      if (document.body && (document.body.clientWidth || document.body.clientHeight)) {
        myWidth = document.body.clientWidth;
        myHeight = document.body.clientHeight;
        setheight(myHeight);
      }
    }
  }
}

function setheight(height) {
  headerEl.style.height = height + 'px';
}

document.addEventListener("DOMContentLoaded", function(event) {
  setWindowSize();
});