干javascript代码 [英] DRY javascript code

问题描述

新手试图学习javasacript和jquery。有人可以帮我干掉这段代码。在我的html网站上运行此代码时，我的CPU使用率很高。任何帮助是极大的赞赏。如何为这样的事件声明变量数组甚至函数？

Newbie trying to learn javasacript and jquery. Can someone help me DRY out this code. I get high CPU usage when running this code on my html website. Any help is greatly appreciated. How do I declare variables array or even functions for something like this?

$(document).ready(function () {

  $("#copy2").animate({
    'position': 'absolute',
    'top': '-390px',
    opacity: 1
  }, 1);
  $(".media-nav2").animate({
    'position': 'absolute',
    'top': '380px',
    opacity: 1
  }, 1);
  $("#copy3").animate({
    'position': 'absolute',
    'top': '-390px',
    opacity: 1
  }, 1);
  $(".media-nav3").animate({
    'position': 'absolute',
    'top': '400px',
    opacity: 1
  }, 1);
  $("#copy4").animate({
    'position': 'absolute',
    'top': '-380px',
    opacity: 1
  }, 1);
  $(".media-nav4").animate({
    'position': 'absolute',
    'top': '400px',
    opacity: 1
  }, 1);
  $("#copy5").animate({
    'position': 'absolute',
    'top': '-390px',
    opacity: 1
  }, 1);
  $(".media-nav5").animate({
    'position': 'absolute',
    'top': '400px',
    opacity: 1
  }, 1);
  $("#copy6").animate({
    'position': 'absolute',
    'top': '-390px',
    opacity: 1
  }, 1);
  $(".media-nav6").animate({
    'position': 'absolute',
    'top': '400px',
    opacity: 1
  }, 1);
  $("#copy7").animate({
    'position': 'absolute',
    'top': '10px',
    opacity: 1
  }, 1);
  $(".media-nav7").animate({
    'position': 'absolute',
    'margin-top': '450px',
    opacity: 1
  }, 1);
  $("#copy8").animate({
    'position': 'absolute',
    'top': '10px',
    opacity: 1
  }, 1);
  $(".media-nav8").animate({
    'position': 'absolute',
    'margin-top': '450px',
    opacity: 1
  }, 1);
  $("#copy9").animate({
    'position': 'absolute',
    'top': '-390px',
    opacity: 1
  }, 1);
  $(".media-nav9").animate({
    'position': 'absolute',
    'top': '400px',
    opacity: 1
  }, 1);
  $("#copy10").animate({
    'position': 'absolute',
    'top': '-390px',
    opacity: 1
  }, 1);
  $(".media-nav10").animate({
    'position': 'absolute',
    'top': '400px',
    opacity: 1
  }, 1);
  $("#copy11").animate({
    'position': 'absolute',
    'top': '-390px',
    opacity: 1
  }, 1);
  $(".media-nav11").animate({
    'position': 'absolute',
    'top': '400px',
    opacity: 1
  }, 1);
  $("#copy12").animate({
    'position': 'absolute',
    'top': '-390px',
    opacity: 1
  }, 1);
  $(".media-nav12").animate({
    'position': 'absolute',
    'top': '400px',
    opacity: 1
  }, 1);
  $("#copy13").animate({
    'position': 'absolute',
    'top': '-390px',
    opacity: 1
  }, 1);
  $(".media-nav13").animate({
    'position': 'absolute',
    'top': '400px',
    opacity: 1
  }, 1);
  $("#copy14").animate({
    'position': 'absolute',
    'top': '-390px',
    opacity: 1
  }, 1);
  $(".media-nav14").animate({
    'position': 'absolute',
    'top': '400px',
    opacity: 1
  }, 1);
  $("#copy15").animate({
    'position': 'absolute',
    'top': '-390px',
    opacity: 1
  }, 1);
  $(".media-nav15").animate({
    'position': 'absolute',
    'top': '400px',
    opacity: 1
  }, 1);
  $("#copy16").animate({
    'position': 'absolute',
    'top': '10px',
    opacity: 1
  }, 1);

  $(function () {

    setInterval(function () {

      $("#copy2").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '0px',
        opacity: 1
      }, 1700);
      $(".media-nav2").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '250px',
        opacity: 1
      }, 1700);
      $("#copy3").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '0px',
        opacity: 1
      }, 1700);
      $(".media-nav3").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '250px',
        opacity: 1
      }, 1700);
      $("#copy4").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '0px',
        opacity: 1
      }, 1700);
      $(".media-nav4").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '250px',
        opacity: 1
      }, 1700);
      $("#copy5").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '0px',
        opacity: 1
      }, 1700);
      $(".media-nav5").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '250px',
        opacity: 1
      }, 1700);
      $("#copy6").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '0px',
        opacity: 1
      }, 1700);
      $(".media-nav6").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '250px',
        opacity: 1
      }, 1700);
      $("#copy7").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '250px',
        opacity: 1
      }, 1700);
      $(".media-nav7").filter(":onScreen").animate({
        'position': 'absolute',
        'margin-top': '250px',
        opacity: 1
      }, 1700);
      $("#copy8").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '250px',
        opacity: 1
      }, 1700);
      $(".media-nav8").filter(":onScreen").animate({
        'position': 'absolute',
        'margin-top': '250px',
        opacity: 1
      }, 1700);
      $("#copy9").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '0px',
        opacity: 1
      }, 1700);
      $(".media-nav9").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '250px',
        opacity: 1
      }, 1700);
      $("#copy10").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '0px',
        opacity: 1
      }, 1700);
      $(".media-nav10").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '250px',
        opacity: 1
      }, 1700);
      $("#copy11").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '0px',
        opacity: 1
      }, 1700);
      $(".media-nav11").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '250px',
        opacity: 1
      }, 1700);
      $("#copy12").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '0px',
        opacity: 1
      }, 1700);
      $(".media-nav12").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '250px',
        opacity: 1
      }, 1700);
      $("#copy13").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '0px',
        opacity: 1
      }, 1700);
      $(".media-nav13").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '250px',
        opacity: 1
      }, 1700);
      $("#copy14").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '0px',
        opacity: 1
      }, 1700);
      $(".media-nav14").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '250px',
        opacity: 1
      }, 1700);
      $("#copy15").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '0px',
        opacity: 1
      }, 1700);
      $(".media-nav15").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '250px',
        opacity: 1
      }, 1700);
      $("#copy16").filter(":onScreen").animate({
        'position': 'absolute',
        'top': '250px',
        opacity: 1
      }, 1700)
    }, 1)

  })

});

推荐答案

我注意到的一些事情：

• 在第一段代码中，我注意到它们都有位置：绝对和不透明度：1 。为什么不将这些样式定义为所有这些元素都具有的类。

• In the first block of code, I notice that they all have position:absolute and opacity:1. Why not define these styles into a class which all these elements will have.

调用animate是多余的。为什么不制作选择器和选项的地图，然后循环遍历它。使您免于冗余的动画调用。我会上课，但问题是每个元素都有不同的选项。

Calling animate is redundant. Why not make a "map" of selector and options and just loop through it. Saves you from the redundant animate calls. I'd do classes but the problem is that each element has different options.

第二个块，以 $开头（函数（）{不需要包含在 $（function（）{中。实际上，这只是<$ c的简写$ c> $（document）.ready（）。

The second block, that starts with $(function () { doesn't need to be wrapped in $(function () {. In fact, that is just a shorthand for $(document).ready().

setInterval 是检查元素可见性的粗略方法。您应该考虑使用 DOM突变事件。免责声明：尚未在所有浏览器上实施。

setInterval is a crude way to check for visibility of the elements. You should consider using DOM Mutation Events. Disclaimer: It's not implemented on all browsers yet.

另外，如果您碰巧注意到，您的间隔设置为永久运行。您没有包含计时器自杀的方法，它将不断查询DOM查询DOM是一个缓慢的过程。你应该设置一个类似标志的东西来表明一切都在屏幕上并且应该杀死它们呃。

Also, if you happen to notice, your interval is set to run forever. You didn't include a way for the timer to kill itself, it will continually query the DOM for elements. Querying the DOM is a slow process. You should set something like a flag to indicate that everything is on screen and should kill the timer.

1ms的间隔是矫枉过正的。有些浏览器将此限制为4毫秒。此外，人类认为200ms或更快是即时，400-600ms是可接受的延迟。

The interval of 1ms is overkill. Some browsers cap this to 4ms. Also, humans consider 200ms or faster as "instant" and 400-600ms as acceptable lag.

由于你有一组静态元素，为什么不缓存它们？将它们与选项一起存储在数组中。

Since you have a static set of elements, why not cache them? Store them in an array, along with the options.

总而言之，它应该如下所示：

All in all, it should look something like this:

var targets = [
  {
    element : $('#copy2'),
    initialAnimationOptions : {...},
    onScreenAnimationOptions : {...}
  },
  ...
];

// Initial animation
$.each(targets,function(index,target){
  target.element.animate(target.initialAnimationOptions);
});

// The crude checker
setInterval(function(){
  $.each(targets,function(index,target){
    if(target.element.is(':onScreen') target.element.animate(target.onScreenAnimationOptions);
  });
},1000);

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