void function() {//abcd 
  do break;while(typeof delete this);
  for(var a;;)
  if (true)  with(null)
  try{}catch(a){}finally{} else throw new 1;
 
  switch(1 in 1 instanceof 1) {
    case false:
    default:
  }
  return;
};

?改进版：

new function() {
    do break;while(typeof delete this);
    for(var a;void 0;)
        continue
    if (null)
        with(0)
    try{
        switch(1 in 1 instanceof 1) {
            case false:
            default:throw true
        }
    }catch(a){}finally{}else return  // console.log("去掉注释可以运行到这里")
};