deeplearnjs-chromeextension-content.js

chrome.runtime.onMessage.addListener(gotMessage)
function gotMessage(message, sender, sendResponse){
  let direction = 0;
  if(message.direction == 'up'){
    direction = -500;
  } else if(message.direction == 'down'){
    direction = +500;
  } else if (message.direction == 'turn off') {
    const mask = document.getElementById('body-maskDiv');
    if (mask) {
      removeMask();
    } else {
      addMask();
    }
  }
  window.scrollBy({ 
    top: direction,
    left: 0, 
    behavior: 'smooth' 
  });
}

function addMask() {
  var maskDiv = document.createElement("div");
  maskDiv.id = 'body-maskDiv';
  maskDiv.setAttribute('style', 'background:rgba(0,0,0,0.6);position:fixed;top:0;width:100%;height:100%;z-index:999');
  var playerContainer = document.getElementById('player-container');
  playerContainer && (playerContainer.style.zIndex = '1001');
  document.body.appendChild(maskDiv);
}

function removeMask() {
  document.getElementById('body-maskDiv').remove();
}