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HTML

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About the <head>

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Insecure Resource

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CSS

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CSS preprocessors help make authoring CSS easier. All of them offer things like variables and mixins to provide convenient abstractions.

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CSS Base

About CSS Base

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Vendor Prefixing

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JavaScript

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Babel includes JSX processing.

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HTML 

              
                <div class="holder">

  <section></section>
  <section class="parallax parallax-1" data-parallax="100"></section>
  <section></section>
  <section>
    <div class="scrollreveal scrollreveal-1">
      Show when enter Viewport
    </div>
  </section>
  <section></section>
  <section class="parallax parallax-2" data-parallax="200">
    <div class="scrollreveal scrollreveal-2">
      Only on first reveal
    </div>
  </section>
  <section></section>
  <section></section>
  <section class="parallax parallax-3" data-parallax="50"></section>
  <section></section>

</div>
!

CSS 

              
                .holder {
  min-height: 2500px;
}

section {
  min-height: 300px;
  padding-top: 70px;
  padding-bottom: 70px;
}

section:nth-child(0) {
  background-color: rgba(255, 0, 0, 0.3);
}

section:nth-child(1) {
  background-color: rgba(0, 128, 0, 0.3);
}

section:nth-child(2) {
  background-color: rgba(255, 255, 0, 0.3);
}

section:nth-child(3) {
  background-color: rgba(0, 0, 255, 0.3);
}

section:nth-child(4) {
  background-color: rgba(0, 0, 0, 0.3);
}

section:nth-child(5) {
  background-color: rgba(0, 255, 255, 0.3);
}

section:nth-child(6) {
  background-color: rgba(255, 165, 0, 0.3);
}

section:nth-child(7) {
  background-color: rgba(255, 192, 203, 0.3);
}

section:nth-child(8) {
  background-color: rgba(128, 128, 128, 0.3);
}

section:nth-child(9) {
  background-color: rgba(0, 0, 139, 0.3);
}

section:nth-child(10) {
  background-color: rgba(0, 128, 0, 0.3);
}

.parallax {
  position: relative;
  background-attachment: fixed;
  background-repeat: no-repeat;
  background-position: 50% 50%;
}

.parallax-1 {
  min-height: 500px;
  background-image: url("https://placekitten.com/g/1900/1280");
}

.parallax-2 {
  background-image: url("https://placekitten.com/g/1900/1230");
}

.parallax-3 {
  background-image: url("https://placekitten.com/g/1900/1300");
}

.scrollreveal { font-size: 60px; color: white; text-align: center; width: 50%; margin: 0 auto; padding: 30px; background-color: rgba(0, 0, 0, 0.2); -webkit-transition: all .5s; transition: all .5s; /*  Hide on default*/ opacity: 0; }

.scrollreveal-2 { -webkit-transition-duration: 2s; transition-duration: 2s; -webkit-transform: scale(0); -ms-transform: scale(0); transform: scale(0); }

.scrollreveal-2.js-revealed { opacity: 1; -webkit-transform: scale(1); -ms-transform: scale(1); transform: scale(1); }

/*  Will be added when item is fully visible, and removed when it's fully out of viewport */
.js-reveal { opacity: 1; }

/*  Will be added the first time item is fully visible  */
.js-revealed { background-color: rgba(0, 0, 0, 0.7); }

/*# sourceMappingURL=style.css.map */
!

JS 

              
                ;
(function($, window, document, undefined) {

  var defaults = {
    viewportSelector: null,

    //Effect could be parallax or scrollReveal
    effectType: 'parallax',

    //Parallax options
    parallaxMaxOffset: 100,

    //Scroll Reveal options

    //Added when item is fully visible, removed when it's fully out of viewport
    scrollRevealedClass: 'js-reveal',

    //Added the first time the item is revealed, it's not remove when the item is hidden
    scrollFirstRevealClass: 'js-revealed',
    autoEnable: true,

    //
    debug: false
  };

  function ScrollEffects(element, options) {

    this.settings = $.extend({}, defaults, options);

    this.$window = $(window);
    this.$viewport = this.settings.viewportSelector ? $(this.settings.viewportSelector) : this.$window;

    this.$elements = $(element);

    this.scrollables = [];

    this.isEnabled = false;

    this.wpWidth = this.$viewport.width();
    this.wpHeight = this.$viewport.height();
    this.scrollTop = 0;

    this.init();
  }

  ScrollEffects.TYPE = {
    PARALLAX: 'parallax',
    SCROLLREVEAL: 'scrollReveal'
  };

  ScrollEffects.prototype = {
    init: function() {
      this.createScrollables();
      if (this.settings.autoEnable) {
        this.enable();
      }
    },

    createScrollables: function() {

      if (this.settings.debug) {
        this.$debug = $('<div />').css({
          'z-index': 1000,
          'position': 'fixed',
          'top': '10px',
          'left': '20px',
          'color': 'white',
          'background-color': 'rgba(0,0,0,.3)',
          'padding': '10px 5px',
          'border-radius': '3px'
        }).text('debug').appendTo($('body'));
      }

      for (var i = 0, j = this.$elements.length; i < j; i++) {

        var $element = this.$elements.eq(i),
          scrollable = {
            $element: $element
          };

        //Parallax
        if (this.settings.effectType == ScrollEffects.TYPE.PARALLAX) {
          scrollable.maxOffset = $.isNumeric($element.data('parallax')) ? parseInt($element.data('parallax')) : this.settings.parallaxMaxOffset;
        }

        //ScrollReveal
        if (this.settings.effectType == ScrollEffects.TYPE.SCROLLREVEAL) {
          scrollable.isFirstReveal = true;
          scrollable.isRevealed = false;
        }

        //ScrollReveal items
        this.scrollables.push(scrollable);
      }
    },

    addEvents: function() {

      this.resetScrollables();
      this.$window.on('resize', $.proxy(this.onResize, this));
      this.$window.on('scroll', $.proxy(this.onScroll, this));

      this.$window.trigger('resize').trigger('scroll');
    },

    resetScrollables: function() {
      if (this.settings.effectType == ScrollEffects.TYPE.PARALLAX) {}

      if (this.settings.effectType == ScrollEffects.TYPE.SCROLLREVEAL) {
        for (var i = 0, j = this.scrollables.length; i < j; i++) {
          var scrollable = this.scrollables[i];
          scrollable.$element.removeClass(this.settings.scrollRevealedClass);
          scrollable.$element.removeClass(this.settings.scrollFirstRevealClass);
          scrollable.isFirstReveal = true;
          scrollable.isRevealed = false;
        }
      }
    },

    onScroll: function() {

      this.scrollTop = this.$window.scrollTop();

      for (var i = 0, j = this.scrollables.length; i < j; i++) {
        var scrollable = this.scrollables[i],
          scrollData = this.getScrollData(scrollable.$element);

        if (this.settings.effectType == ScrollEffects.TYPE.PARALLAX) {
          this.processParallaxItem(scrollable, scrollData);
        }
        if (this.settings.effectType == ScrollEffects.TYPE.SCROLLREVEAL) {
          this.processScrollRevealItem(scrollable, scrollData);
        }

      }

    },

    processParallaxItem: function(_scrollable, _scrollData) {

      if (_scrollData.isVisible) {
        var offset = this.percentToRange(_scrollData.percentEntered, -_scrollable.maxOffset, _scrollable.maxOffset);
        _scrollable.$element.css({
          'background-position': '50% ' + parseInt(offset) + 'px'
        });
      }
    },

    processScrollRevealItem: function(_scrollable, _scrollData) {
      if (!_scrollable.isRevealed && _scrollData.isFullyEntered) {
        _scrollable.$element.addClass(this.settings.scrollRevealedClass);
        if (_scrollable.isFirstReveal) {
          _scrollable.isFirstReveal = false;
          _scrollable.$element.addClass(this.settings.scrollFirstRevealClass);
        }
        _scrollable.isRevealed = true;
      }

      if (_scrollable.isRevealed && _scrollData.isFullyExited) {
        _scrollable.isRevealed = false;
        _scrollable.$element.removeClass(this.settings.scrollRevealedClass);
      }
    },

    onResize: function() {
      this.wpWidth = this.$viewport.width();
      this.wpHeight = this.$viewport.height();
    },

    //--------------------------------------------------------------
    //  Return percent from 0 to 1
    //  0.01 when element is almost at the top
    //  0.99 when just entered from bottom
    //--------------------------------------------------------------

    getScrollData: function(_$element) {

      var viewPortData = {
        isVisible: false,
        isFullyEntered: false,
        isFullyExited: true,
        percentEntered: 0
      };
      
      
      var elementHeight = _$element.outerHeight(),
        boundRect = _$element.get(0).getBoundingClientRect(),
        elementTop = boundRect.top,
        elementBottom = boundRect.bottom;
      if (elementTop >= -elementHeight && elementBottom <= (this.wpHeight + elementHeight)) {
        viewPortData.isVisible = true;
        viewPortData.isFullyEntered = elementTop >= 0 && elementBottom <= this.wpHeight;
        viewPortData.percentEntered = this.rangeToPercent(elementTop, -elementHeight, this.wpHeight);
        viewPortData.isFullyExited = viewPortData.percentEntered == 0;
      }

      return viewPortData;
    },

    enable: function() {

      if (!this.isEnabled) {
        this.isEnabled = true;
        this.resetScrollables();
        this.addEvents();
      }
    },

    disable: function(_normalize) {

      if (this.isEnabled) {
        this.isEnabled = false;

        this.$window.off('scroll', $.proxy(this.onScroll, this));
        this.$window.off('resize', $.proxy(this.onResize, this));

        if (_normalize) {
          if (this.settings.effectType == ScrollEffects.TYPE.PARALLAX) {
            this.$elements.css({
              'background-position': '50% 50%'
            });
          } else if (this.settings.effectType == ScrollEffects.TYPE.SCROLLREVEAL) {
            for (var i = 0, j = this.scrollables.length; i < j; i++) {
              var scrollable = this.scrollables[i];
              scrollable.$element.addClass(this.settings.scrollRevealedClass);
              scrollable.$element.addClass(this.settings.scrollFirstRevealClass);
            }
          }
        }
      }
    },

    //--------------------------------------------------------------
    //  UTILS
    //--------------------------------------------------------------
    rangeToPercent: function(_number, _min, _max) {
      return ((_number - _min) / (_max - _min));
    },

    percentToRange: function(_percent, _min, _max) {
      return ((_max - _min) * _percent + _min);
    }

  };

  window.ScrollEffects = ScrollEffects;

})(jQuery, window, document);

//

$(function() {

  var parallax = new ScrollEffects('.parallax', {
    effectType: 'parallax'
  });

  var scrollShow = new ScrollEffects('.scrollreveal', {
    effectType: 'scrollReveal'
  });

  var $window = $(window);
  $window.on('resize', function() {

    if ($window.width() >= 900) {
      parallax.enable();
      scrollShow.enable();
    } else {
      parallax.disable(true);
      scrollShow.disable(true);
    }
  }).trigger('resize');

});
!
999px

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