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HTML

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HTML preprocessors can make writing HTML more powerful or convenient. For instance, Markdown is designed to be easier to write and read for text documents and you could write a loop in Pug.

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About the <head>

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Insecure Resource

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CSS

About CSS Preprocessors

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

It's a common practice to apply CSS to a page that styles elements such that they are consistent across all browsers. We offer two of the most popular choices: normalize.css and a reset. Or, choose Neither and nothing will be applied.

Vendor Prefixing

About Vendor Prefixing

To get the best cross-browser support, it is a common practice to apply vendor prefixes to CSS properties and values that require them to work. For instance -webkit- or -moz-.

We offer two popular choices: Autoprefixer (which processes your CSS server-side) and -prefix-free (which applies prefixes via a script, client-side).

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JavaScript

About JavaScript Preprocessors

JavaScript preprocessors can help make authoring JavaScript easier and more convenient.

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Babel includes JSX processing.

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Packages

Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.

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Using packages here is powered by Skypack, which makes packages from npm not only available on a CDN, but prepares them for native JavaScript ES6 import usage.

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HTML 

              
                <div id="box-1" class="box">1</div>
<div id="box-2" class="box">2</div>
<div id="box-3" class="box">3</div>
<div id="box-4" class="box">4</div>
<div id="box-4" class="box">5</div>
!

CSS 

              
                .box {
  width: 75px;
  height: 75px;
  background: green;
  margin: 10px;
  color: #fff;
  font-size: 24px;
  font-weight: bold;
  text-align: center;
  line-height: 75px;
  text-shadow: 0px 0px 1px rgba(0,0,0,1);
}
!

JS 

              
                console.clear();

var offset = 25;
var $boxes = $(".box");

$boxes.each(function(i) {
  var color = "hsl(" + i / $boxes.length * 360 + ", 100%, 50%)";
  TweenLite.set(this, { x: 0, backgroundColor: color });
});

//
// BOX 1: Constructor using class declaration
// ===========================================================================
class Box1 {  
  constructor() {
    this.element = $boxes[0];
  }
  
  get x() { return this.element._gsTransform.x; }
  set x(x) {
    x = Math.round(x / offset) * offset;
    if (this.x !== x) {
      TweenLite.set(this.element, { x: x });
    }
  }
}

//
// BOX 2: Constructor without class declaration
// ===========================================================================
function Box2() {
  this.element = $boxes[1];
}

Object.defineProperty(Box2.prototype, "x", {
    get: function () { return this.element._gsTransform.x; },
    set: function (x) {
      x = Math.round(x / offset) * offset;
      if (this.x !== x) {
        TweenLite.set(this.element, { x: x });
      }
    }
});

//
// BOX 3: Object literal
// ===========================================================================
var box3 = {
  element: $boxes[2],
  get x() { return this.element._gsTransform.x; },
  set x(x) {
    x = Math.round(x / offset) * offset;
    if (this.x !== x) {
      TweenLite.set(this.element, { x: x });
    }
  }
};


//
// BOX 4: Using a single function based getter/setter
// ===========================================================================
var box4 = {
  element: $boxes[3],
  x: function(x) {
    
    var lastX = this.element._gsTransform.x;
    
    if (!arguments.length) {
      return lastX;
    }
    
    x = Math.round(x / offset) * offset;
    if (lastX !== x) {
      TweenLite.set(this.element, { x: x });
    }
  }
};

//
// BOX 5: Using functions prefixed with "get" and "set"
// ===========================================================================
var box5 = {
  element: $boxes[4],
  getX: function() {
    return this.element._gsTransform.x;
  },
  setX: function(x) {
    x = Math.round(x / offset) * offset;
    if (this.getX() !== x) {
      TweenLite.set(this.element, { x: x });
    }
  }
};

// Box 1 and 2 use a constructor
var box1 = new Box1();
var box2 = new Box2();

var tl = new TimelineMax({ repeat: -1, repeatDelay: 0.5, yoyo: true });

tl.to([box1, box2, box3, box4], 2, { x: 500 }, 0)
  .to(box5, 2, { setX: 500 }, 0);
!
999px

Console