在视口中为计数器设置动画

Question

我有一个计数器,动画到HTML中定义的最终数字.但是我希望这个动画一旦在视口中就会发​​生.

我在这里有一个小提琴,显示滚动似乎如何影响计数器编号.

$(document).ready(function() {
      $(function($, win) {
        $.fn.inViewport = function(cb) {
          return this.each(function(i, el) {
            function visPx() {
              var H = $(this).height(),
                r = el.getBoundingClientRect(),
                t = r.top,
                b = r.bottom;
              return cb.call(el, Math.max(0, t > 0 ? H - t : (b < H ? b : H)));
            }
            visPx();
            $(win).on("resize scroll", visPx);
          });
        };
      }(jQuery, window));

      $(".fig-number").inViewport(function(px) {
        $(this).each(function() {
          $(this).prop('Counter', 0).animate({
            Counter: $(this).text()
          }, {
            duration: 1000,

            step: function(now) {
              $(this).text(Math.ceil(now));
            }
          });
        });
      });
    });

我尝试了很多东西,但我似乎无法实现我所追求的目标.

$(document).ready(function() {
  $(function($, win) {
    $.fn.inViewport = function(cb) {
      return this.each(function(i, el) {
        function visPx() {
          var H = $(this).height(),
            r = el.getBoundingClientRect(),
            t = r.top,
            b = r.bottom;
          return cb.call(el, Math.max(0, t > 0 ? H - t : (b < H ? b : H)));
        }
        visPx();
        $(win).on("resize scroll", visPx);
      });
    };
  }(jQuery, window));

  $(".fig-number").inViewport(function(px) {
    $(this).each(function() {
      $(this).prop('Counter', 0).animate({
        Counter: $(this).text()
      }, {
        duration: 1000,

        step: function(now) {
          $(this).text(Math.ceil(now));
        }
      });
    });
  });
});

html,
body {
  height: 100%;
}
#upper-push {
  height: 100%;
  width: 100%;
  display: block;
  background: red;
  color: white;
}

<div id="upper-push">
  Scroll down
</div>
<div id="numbers">
  <span class="fig-number">25</span>
  <span class="fig-number">78</span>
</div>

Answer 1

该.inViewport()插件触发每个滚动事件的回调.
这是设计的.(有助于在代码中保留插件的来源!;))

在"插件页面"上,您可以看到如何使用它:

$("selector").inViewport(function(px) {
  console.log( px ); // `px` represents the amount of visible height
  if(px){
    // do this if element enters the viewport // px > 0
  }else{
    // do that if element exits  the viewport // px = 0
  }
}); // Here you can chain other jQuery methods to your selector 

这意味着:

1. 你必须监听px参数大于0(元素在视口中)
2. 要防止链接其他动画创建构建,您应该使用标志变量
3. ($(this).each()不需要回调内部.插件已经在一组元素上运行.)

编辑jsFiddle演示

jQuery(function($) { // DOM ready and $ in scope

  $(".fig-number").inViewport(function(px) {
    // if px>0 (entered V.port) and
    // if prop initNumAnim flag is not yet set = Animate numbers
    if(px>0 && !this.initNumAnim) { 
      this.initNumAnim = true; // Set flag to true to prevent re-running the same animation
      // <<< DO SOME COOL STUFF HERE! 
    }
  });

});

片段示例:

// inViewport jQuery plugin
// https://stackoverflow.com/a/26831113/383904
$(function($, win) {
  $.fn.inViewport = function(cb) {
    return this.each(function(i,el){
      function visPx(){
        var H = $(this).height(),
            r = el.getBoundingClientRect(), t=r.top, b=r.bottom;
        return cb.call(el, Math.max(0, t>0? H-t : (b<H?b:H)));  
      } visPx();
      $(win).on("resize scroll", visPx);
    });
  };
}(jQuery, window));


jQuery(function($) { // DOM ready and $ in scope

  $(".fig-number").inViewport(function(px) { // Make use of the `px` argument!!!
    // if element entered V.port ( px>0 ) and
    // if prop initNumAnim flag is not yet set
    //  = Animate numbers
    if(px>0 && !this.initNumAnim) { 
      this.initNumAnim = true; // Set flag to true to prevent re-running the same animation
      $(this).prop('Counter',0).animate({
        Counter: $(this).text()
      }, {
        duration: 1000,
        step: function (now) {
          $(this).text(Math.ceil(now));
        }
      });         
    }
  });

});

html,
body {
  height:100%;
}

#upper-push {
  height:100%;
  width:100%;
  display:block;
  background:red;
  color:white;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="upper-push">
  Scroll down
</div>
<div id="numbers">
  <span class="fig-number">25</span>
  <span class="fig-number">78</span>
</div>

Answer 2

如果您不介意更改代码,这可以解决它. 的jsfiddle

    var $findme = $('#numbers');
var exec = false;
function Scrolled() {
  $findme.each(function() {
    var $section = $(this),
      findmeOffset = $section.offset(),
      findmeTop = findmeOffset.top,
      findmeBottom = $section.height() + findmeTop,
      scrollTop = $(document).scrollTop(),
      visibleBottom = window.innerHeight,
      prevVisible = $section.prop('_visible');

    if ((findmeTop > scrollTop + visibleBottom) ||
      findmeBottom < scrollTop) {
      visible = false;
    } else visible = true;

    if (!prevVisible && visible) {
    	if(!exec){
              $('.fig-number').each(function() {
          $(this).prop('Counter', 0).animate({
            Counter: $(this).text()
          }, {
            duration: 1000,

            step: function(now) {
              $(this).text(Math.ceil(now));
              exec = true;
            }
          });
        });
      }
    }
    $section.prop('_visible', visible);
  });

}

function Setup() {
  var $top = $('#top'),
    $bottom = $('#bottom');

  $top.height(500);
  $bottom.height(500);

  $(window).scroll(function() {
    Scrolled();
  });
}
$(document).ready(function() {
  Setup();
});

html,
body {
  height: 100%;
}

#upper-push {
  height: 100%;
  width: 100%;
  display: block;
  background: red;
  color: white;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="upper-push">
  Scroll down
</div>
<div id="numbers">
  <span class="fig-number">25</span>
  <span class="fig-number">78</span>
</div>