54 lines
1.2 KiB
HTML
54 lines
1.2 KiB
HTML
<!DOCTYPE HTML>
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<html>
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<head>
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<meta charset="utf-8">
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</head>
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<body>
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<script>
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function preloadImages(sources, callback) {
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let counter = 0;
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function onLoad() {
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counter++;
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if (counter == sources.length) callback();
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}
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for(let source of sources) {
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let img = document.createElement('img');
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img.onload = img.onerror = onLoad;
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img.src = source;
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}
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}
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// ---------- The test ----------
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let sources = [
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"https://en.js.cx/images-load/1.jpg",
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"https://en.js.cx/images-load/2.jpg",
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"https://en.js.cx/images-load/3.jpg"
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];
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// add random characters to prevent browser caching
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for (let i = 0; i < sources.length; i++) {
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sources[i] += '?' + Math.random();
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}
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// for each image,
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// let's create another img with the same src and check that we have its width
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function testLoaded() {
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let widthSum = 0;
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for (let i = 0; i < sources.length; i++) {
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let img = document.createElement('img');
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img.src = sources[i];
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widthSum += img.width;
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}
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alert(widthSum);
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}
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// should output 300
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preloadImages(sources, testLoaded);
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</script>
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</body>
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</html>
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