Javascript 根据滚动条位置更改元素的不透明度

我试图根据滚动条的位置改变元素的不透明度，但是函数总是会在第一个“else if”之后停止，因此即使函数仍然检测到滚动条的位置，元素“C”、“D”、“E”也不会发生任何变化

$(document).ready(function() {   
      $(window).scroll(function(event) {
        var scroll = $(window).scrollTop();

      if (scroll < 600) {
        document.getElementById("A").style.opacity = "1";
        document.getElementById("B").style.opacity = "0.5";
        document.getElementById("C").style.opacity = "0.5";
        document.getElementById("D").style.opacity = "0.5";
      } 
      else if (600 <= scroll < 1500) {
        document.getElementById("A").style.opacity = "0.5";
        document.getElementById("B").style.opacity = "1";
        document.getElementById("C").style.opacity = "0.5";
        document.getElementById("D").style.opacity = "0.5";
      } 
      else if (1500 <= scroll < 2600) {
        document.getElementById("A").style.opacity = "0.5";
        document.getElementById("B").style.opacity = "0.5";
        document.getElementById("C").style.opacity = "1";
        document.getElementById("D").style.opacity = "0.5";
      } 
      else if (2600 <= scroll < 3200) {
        document.getElementById("A").style.opacity = "0.5";
        document.getElementById("B").style.opacity = "0.5";
        document.getElementById("C").style.opacity = "0.5";
        document.getElementById("D").style.opacity = "1";

$（文档）.ready（函数（）{
$（窗口）。滚动（功能（事件）{
var scroll=$（窗口）.scrollTop（）；
如果（滚动<600）{
document.getElementById（“A”）.style.opacity=“1”；
document.getElementById（“B”）.style.opacity=“0.5”；
document.getElementById（“C”）.style.opacity=“0.5”；
document.getElementById（“D”）.style.opacity=“0.5”；
} 
否则，如果（600你不能做x
$(document).ready(function() {   
  $(window).scroll(function(event) {
    var scroll = $(window).scrollTop();

  if (scroll < 600) {
    document.getElementById("A").style.opacity = "1";
    document.getElementById("B").style.opacity = "0.5";
    document.getElementById("C").style.opacity = "0.5";
    document.getElementById("D").style.opacity = "0.5";
  } 
  else if (600 <= scroll && scroll < 1500) {
    document.getElementById("A").style.opacity = "0.5";
    document.getElementById("B").style.opacity = "1";
    document.getElementById("C").style.opacity = "0.5";
    document.getElementById("D").style.opacity = "0.5";
  } 
  else if (1500 <= scroll && scroll < 2600) {
    document.getElementById("A").style.opacity = "0.5";
    document.getElementById("B").style.opacity = "0.5";
    document.getElementById("C").style.opacity = "1";
    document.getElementById("D").style.opacity = "0.5";
  } 
  else if (2600 <= scroll && scroll < 3200) {
    document.getElementById("A").style.opacity = "0.5";
    document.getElementById("B").style.opacity = "0.5";
    document.getElementById("C").style.opacity = "0.5";
    document.getElementById("D").style.opacity = "1";

$（文档）.ready（函数（）{
$（窗口）。滚动（功能（事件）{
var scroll=$（窗口）.scrollTop（）；
如果（滚动<600）{
document.getElementById（“A”）.style.opacity=“1”；
document.getElementById（“B”）.style.opacity=“0.5”；
document.getElementById（“C”）.style.opacity=“0.5”；
document.getElementById（“D”）.style.opacity=“0.5”；
} 
否则，如果（600天哪，我太笨了xD，谢谢你的工作！对不起，我对这东西有点陌生