JavaScript code and bookmarklet to cancel annoying "Please disable ad blocker" overlays that cover the page and disable scrolling

removeOverlay.js

// find the element in the body with max z-index
// adapted from this StackOverflow answer by Jimmy Chandra:
//   https://stackoverflow.com/a/1118216/470925
let max, maxVal = 0
document.querySelectorAll('body *').forEach(el => {
  // get position and zIndex style values for the element
  const {position, zIndex} = document.defaultView.getComputedStyle(el)
  // skip statically positioned elements
  if (position !== 'static') {
    // parse the string value of zIndex into an integer, defaulting to 1,
    // e.g. if the value is "auto" and parseInt produces NaN
    const z = parseInt(zIndex) || 1
    // if this is the largest zIndex we've seen, store it
    if (z > maxVal) {
      maxVal = z
      max = el
    }
  }
})
// chances are, max now holds the overlay element; delete it
max.remove()
// most of these overlay tricks also set body and html overflowY to "hidden",
// so reset both back to "auto" as they should be so you can scroll the page
document.body.style.overflowY = document.body.parentElement.style.overflowY = 'auto'

removeOverlayBookmarklet.js

// create a new bookmark with this in the URL field; it's the same code as above, just minified
javascript:(_=>{let d=document,b=d.body,v=0,m;d.querySelectorAll('body *').forEach(e=>{let {position:p,zIndex:i}=d.defaultView.getComputedStyle(e);if(p!=='static'){let z=parseInt(i)||1;if(z>v){v=z;m=e}}});m.remove();b.style.overflowY=b.parentElement.style.overflowY='auto'})()