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<h1><a href="index.html">lib.</a>Image Loader Worker</h1>
<p>
The loading of multiple small images (e.g. loadimng tiles of a zoomable map) is a time consuming task that
leads to small but noticeable delays in touch interaction if standard DOM events are used. With a worker we
can try to do most of the time consuming processing in the background.
</p>
<p>Let's look at an example of a image loader worker:</p>
<img id="img1" width="160" height="120" class="grayBorder interactive" src="" />
<img id="img2" width="160" height="120" class="grayBorder interactive" src="" />
<img id="img3" width="160" height="120" class="grayBorder interactive" src="" />
<img id="img4" width="160" height="120" class="grayBorder interactive" src="" />
<script class="doctest">
let urls = [
'http://i.imgur.com/JmvCQXd.jpg',
'http://i.imgur.com/L4ipvCE.jpg',
'http://i.imgur.com/fKDIYIP.jpg',
'http://i.imgur.com/4ad4bo5.jpg'
]
let imgs = [img1, img2, img3, img4]
let count = 0
let worker = new Worker('imageloader.js')
worker.onmessage = (event) => {
console.log('Loaded', event.data)
if (event.data.success) {
console.log('Loaded', event.data.url)
imgs[count].src = event.data.url
count += 1
}
}
worker.postMessage({ command: 'load', urls: urls })
worker.postMessage({ command: 'abort', urls: urls })
worker.postMessage({ command: 'load', urls: urls })
</script>
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