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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-.

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About JavaScript Preprocessors

JavaScript preprocessors can help make authoring JavaScript easier and more convenient. For instance, CoffeeScript can help prevent easy-to-make mistakes and offer a cleaner syntax and Babel can bring ECMAScript 6 features to browsers that only support ECMAScript 5.

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You're using npm packages, so we've auto-selected Babel for you here, which we require to process imports and make it all work. If you need to use a different JavaScript preprocessor, remove the packages in the npm tab.

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About External Resources

You can apply a script from anywhere on the web to your Pen. Just put a URL to it here and we'll add it, in the order you have them, before the JavaScript in the Pen itself.

If the script you link to has the file extension of a preprocessor, we'll attempt to process it before applying.

You can also link to another Pen here, and we'll pull the JavaScript from that Pen and include it. If it's using a matching preprocessor, we'll combine the code before preprocessing, so you can use the linked Pen as a true dependency.

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Next Step Leave tour

HTML

            
              <button id="cake">Take Screeny</button>

<br />

<canvas id="fake"></canvas>
!

JS

            
              const canIRun  = navigator.mediaDevices.getDisplayMedia 

const takeScreenShot = async () => {
      const stream = await navigator.mediaDevices.getDisplayMedia({
        video: { mediaSource: 'screen' },
      })
      // get correct video track
      const track = stream.getVideoTracks()[0]
      // init Image Capture and not Video stream
      const imageCapture = new ImageCapture(track)
      // take first frame only
      const bitmap = await imageCapture.grabFrame()
      // destory video track to prevent more recording / mem leak
      track.stop()

      const canvas = document.getElementById('fake') 
      // this could be a document.createElement('canvas') if you want
      // draw weird image type to canvas so we can get a useful image
      canvas.width = bitmap.width
      canvas.height = bitmap.height
      const context = canvas.getContext('2d')
      context.drawImage(bitmap, 0, 0, bitmap.width, bitmap.height)
      const image = canvas.toDataURL()

      // this turns the base 64 string to a [File] object
      const res = await fetch(image)
      const buff = await res.arrayBuffer()
      // clone so we can rename, and put into array for easy proccessing
      const file = [
        new File([buff], `photo_${new Date()}.jpg`, {
          type: 'image/jpeg',
        }),
      ]
      return file 
}     

const button = document.getElementById('cake').onclick = () => canIRun ? takeScreenShot() : {}
!
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