39 lines
1.2 KiB
JavaScript
39 lines
1.2 KiB
JavaScript
function request_image(url) {
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return new Promise(function(resolve, reject) {
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var img = new Image();
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var settled = false;
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function settleOk() {
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if (settled) return;
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settled = true;
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clearTimeout(failTimer);
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img.onload = img.onerror = null;
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resolve(img);
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}
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function settleFail() {
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if (settled) return;
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settled = true;
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clearTimeout(failTimer);
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img.onload = img.onerror = null;
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reject(url);
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}
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img.onload = settleOk;
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img.onerror = settleFail;
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img.src = url + '?random-no-cache=' + Math.floor((1 + Math.random()) * 0x10000).toString(16);
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var failTimer = setTimeout(settleFail, 5000);
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});
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}
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function ping(url, multiplier) {
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return new Promise(function(resolve, reject) {
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var start = (new Date()).getTime();
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var response = function() {
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var delta = ((new Date()).getTime() - start);
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delta *= (multiplier || 1);
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resolve(delta);
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};
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request_image(url).then(response).catch(response);
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});
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}
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export default ping;
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