为什么我的javascript无法用于视差效果？

Question

我是HTML5，CSS3和JavaScript的新手，所以请不要苛刻。

我正在尝试在我的网页上创建一个视差效果，但菜单栏会一直滚动效果，一旦到达顶部，它应该位于屏幕顶部的固定位置。我尝试将HTML文件链接到CSS文件和JavaScript文件。当这不起作用时，我尝试在脚本标签中添加样式标签和JavaScript中的CSS代码，结果是一样的。我正在使用Dreamweaver CC。

所以我在网上找到了一个提供完美效果的例子，但是它使用JavaScript，每当我尝试使用JavaScript时它都无法运行。有人可以告诉我，我做错了。我从https://codepen.io/nodws/pen/ugFcC得到了例子。我真的想把这种风格融入我的页面，但如果我甚至无法让这个例子起作用，那么我就迷失了。

我尝试将HTML文件链接到CSS文件和JavaScript文件，将相应的代码放在相应的文件中。当这不起作用时，我尝试在脚本标签中添加样式标签和JavaScript中的CSS代码，结果是一样的。我正在使用Dreamweaver CC。

//Based on the Scroller function from @sallar
var $content = $('header .content'),
  $blur = $('header .overlay'),
  wHeight = $(window).height();

$(window).on('resize', function() {
  wHeight = $(window).height();
});

window.requestAnimFrame = (function() {
  return window.requestAnimationFrame ||
    window.webkitRequestAnimationFrame ||
    window.mozRequestAnimationFrame ||
    function(callback) {
      window.setTimeout(callback, 1000 / 60);
    };
})();

function Scroller() {
  this.latestKnownScrollY = 0;
  this.ticking = false;
}

Scroller.prototype = {

  init: function() {
    window.addEventListener('scroll', this.onScroll.bind(this), false);
    $blur.css('background-image', $('header:first-of-type').css('background-image'));
  },


  onScroll: function() {
    this.latestKnownScrollY = window.scrollY;
    this.requestTick();
  },


  requestTick: function() {
    if (!this.ticking) {
      window.requestAnimFrame(this.update.bind(this));
    }
    this.ticking = true;
  },

  update: function() {
    var currentScrollY = this.latestKnownScrollY;
    this.ticking = false;

    var slowScroll = currentScrollY / 2,
      blurScroll = currentScrollY * 2,
      opaScroll = 1.4 - currentScrollY / 400;
    if (currentScrollY > wHeight)
      $('nav').css('position', 'fixed');
    else
      $('nav').css('position', 'absolute');

    $content.css({
      'transform': 'translateY(' + slowScroll + 'px)',
      '-moz-transform': 'translateY(' + slowScroll + 'px)',
      '-webkit-transform': 'translateY(' + slowScroll + 'px)',
      'opacity': opaScroll
    });

    $blur.css({
      'opacity': blurScroll / wHeight
    });
  }
};


var scroller = new Scroller();
scroller.init();

@import url(https://fonts.googleapis.com/css?family=Lato);
html,
body {
  padding: 0;
  margin: 0;
  height: 100%;
}

html {
  font: 1em/1.5 "Lato", sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizelegibility;
}

body {
  font-size: 1.3em;
}

header {
  height: 100%;
  position: relative;
  overflow: hidden;
  background: url(https://unsplash.imgix.net/45/ZLSw0SXxThSrkXRIiCdT_DSC_0345.jpg?q=75&w=1080&h=1080&fit=max&fm=jpg&auto=format&s=857f07b76abac23a7fb7161cc7b12a46) center no-repeat;
  /* Image Credit: Unsplash.me */
  background-size: cover;
}

header .content {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 1;
}

header h1,
header h2 {
  margin: 0;
}

header h2 {
  text-transform: uppercase;
  margin-top: -.5em;
}

header hgroup {
  -webkit-transform: translate(-50%, -50%);
  -moz-transform: translate(-50%, -50%);
  -ms-transform: translate(-50%, -50%);
  -o-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
  display: inline-block;
  text-align: center;
  position: absolute;
  top: 50%;
  left: 50%;
  color: #fff;
  border: 5px solid #fff;
  padding: .5em 3em;
  background-color: rgba(0, 0, 0, 0.2);
  z-index: 2;
}

header .overlay {
  position: absolute;
  top: 0;
  right: 0;
  left: 0;
  bottom: 0;
  background: #333 center no-repeat;
  background-size: cover;
  z-index: 0;
  opacity: 0;
  -webkit-filter: blur(4px);
}

img {
  margin-right: 20px
}

.site {
  padding: 20em 0;
  text-align: center;
  background-color: #efefef;
  font-size: .8em;
  color: #444;
  position: relative
}

.site a {
  color: #666;
  text-decoration: none;
}

.site a:hover {
  color: #222;
}

.site nav {
  position: absolute;
  top: 0;
  left: 0;
  background: #222;
  width: 100%
}

.site nav a {
  padding: 10px 30px;
  font-size: 1.3em;
  display: inline-block
}

.site nav a:hover {
  background: #333;
  color: #fff
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<!doctype html>
<html>

<head>
  <meta charset="utf-8">
  <title>test</title>
</head>

<body>

  <header>
    <div class="content">
      <hgroup>
        <h1>LOGO</h1>
        <i>slogan</i>
      </hgroup>
    </div>
    <div class="overlay"></div>
  </header>
  <section class="site">
    <nav>
      <a href="">Page</a>
      <a href="">Page</a>
      <a href="">Page</a>
      <a href="">Page</a>
      <a href="">Page</a>
    </nav>
    <blockquote>
      <img src="http://d.gr-assets.com/authors/1397426898p5/203714.jpg" align="left">“I invented nothing new. I simply assembled the discoveries of other men behind whom were centuries of work. Had I worked fifty or ten or even five years before, I would
      have failed. So it is with every new thing. Progress happens when all the factors that make for it are ready, and then it is inevitable. To teach that a comparatively few men are responsible for the greatest forward steps of mankind is the worst
      sort of nonsense.” ― Henry Ford
    </blockquote>
  </section>
</body>


</html>

Answer 1

您似乎缺少对jQuery的引用

＆＃13;

＆＃13;

//Based on the Scroller function from @sallar
var $content = $('header .content'),
  $blur = $('header .overlay'),
  wHeight = $(window).height();

$(window).on('resize', function() {
  wHeight = $(window).height();
});

window.requestAnimFrame = (function() {
  return window.requestAnimationFrame ||
    window.webkitRequestAnimationFrame ||
    window.mozRequestAnimationFrame ||
    function(callback) {
      window.setTimeout(callback, 1000 / 60);
    };
})();

function Scroller() {
  this.latestKnownScrollY = 0;
  this.ticking = false;
}

Scroller.prototype = {

  init: function() {
    window.addEventListener('scroll', this.onScroll.bind(this), false);
    $blur.css('background-image', $('header:first-of-type').css('background-image'));
  },


  onScroll: function() {
    this.latestKnownScrollY = window.scrollY;
    this.requestTick();
  },


  requestTick: function() {
    if (!this.ticking) {
      window.requestAnimFrame(this.update.bind(this));
    }
    this.ticking = true;
  },

  update: function() {
    var currentScrollY = this.latestKnownScrollY;
    this.ticking = false;

    var slowScroll = currentScrollY / 2,
      blurScroll = currentScrollY * 2,
      opaScroll = 1.4 - currentScrollY / 400;
    if (currentScrollY > wHeight)
      $('nav').css('position', 'fixed');
    else
      $('nav').css('position', 'absolute');

    $content.css({
      'transform': 'translateY(' + slowScroll + 'px)',
      '-moz-transform': 'translateY(' + slowScroll + 'px)',
      '-webkit-transform': 'translateY(' + slowScroll + 'px)',
      'opacity': opaScroll
    });

    $blur.css({
      'opacity': blurScroll / wHeight
    });
  }
};


var scroller = new Scroller();
scroller.init();

＆＃13;

@import url(https://fonts.googleapis.com/css?family=Lato);
html,
body {
  padding: 0;
  margin: 0;
  height: 100%;
}

html {
  font: 1em/1.5 "Lato", sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizelegibility;
}

body {
  font-size: 1.3em;
}

header {
  height: 100%;
  position: relative;
  overflow: hidden;
  background: url(https://unsplash.imgix.net/45/ZLSw0SXxThSrkXRIiCdT_DSC_0345.jpg?q=75&w=1080&h=1080&fit=max&fm=jpg&auto=format&s=857f07b76abac23a7fb7161cc7b12a46) center no-repeat;
  /* Image Credit: Unsplash.me */
  background-size: cover;
}

header .content {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 1;
}

header h1,
header h2 {
  margin: 0;
}

header h2 {
  text-transform: uppercase;
  margin-top: -.5em;
}

header hgroup {
  -webkit-transform: translate(-50%, -50%);
  -moz-transform: translate(-50%, -50%);
  -ms-transform: translate(-50%, -50%);
  -o-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
  display: inline-block;
  text-align: center;
  position: absolute;
  top: 50%;
  left: 50%;
  color: #fff;
  border: 5px solid #fff;
  padding: .5em 3em;
  background-color: rgba(0, 0, 0, 0.2);
  z-index: 2;
}

header .overlay {
  position: absolute;
  top: 0;
  right: 0;
  left: 0;
  bottom: 0;
  background: #333 center no-repeat;
  background-size: cover;
  z-index: 0;
  opacity: 0;
  -webkit-filter: blur(4px);
}

img {
  margin-right: 20px
}

.site {
  padding: 20em 0;
  text-align: center;
  background-color: #efefef;
  font-size: .8em;
  color: #444;
  position: relative
}

.site a {
  color: #666;
  text-decoration: none;
}

.site a:hover {
  color: #222;
}

.site nav {
  position: absolute;
  top: 0;
  left: 0;
  background: #222;
  width: 100%
}

.site nav a {
  padding: 10px 30px;
  font-size: 1.3em;
  display: inline-block
}

.site nav a:hover {
  background: #333;
  color: #fff
}

＆＃13;

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<!doctype html>
<html>

<head>
  <meta charset="utf-8">
  <title>test</title>
</head>

<body>

  <header>
    <div class="content">
      <hgroup>
        <h1>LOGO</h1>
        <i>slogan</i>
      </hgroup>
    </div>
    <div class="overlay"></div>
  </header>
  <section class="site">
    <nav>
      <a href="">Page</a>
      <a href="">Page</a>
      <a href="">Page</a>
      <a href="">Page</a>
      <a href="">Page</a>
    </nav>
    <blockquote>
      <img src="http://d.gr-assets.com/authors/1397426898p5/203714.jpg" align="left">“I invented nothing new. I simply assembled the discoveries of other men behind whom were centuries of work. Had I worked fifty or ten or even five years before, I would
      have failed. So it is with every new thing. Progress happens when all the factors that make for it are ready, and then it is inevitable. To teach that a comparatively few men are responsible for the greatest forward steps of mankind is the worst
      sort of nonsense.” ― Henry Ford
    </blockquote>
  </section>
</body>


</html>

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＆＃13;

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