79 lines
1.8 KiB
JavaScript
79 lines
1.8 KiB
JavaScript
"use strict";
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exports.__esModule = true;
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exports.default = void 0;
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const support = function (feature) {
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if (typeof document === `undefined`) {
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return false;
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}
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const fakeLink = document.createElement(`link`);
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try {
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if (fakeLink.relList && typeof fakeLink.relList.supports === `function`) {
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return fakeLink.relList.supports(feature);
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}
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} catch (err) {
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return false;
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}
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return false;
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};
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const linkPrefetchStrategy = function (url, options) {
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return new Promise((resolve, reject) => {
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if (typeof document === `undefined`) {
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reject();
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return;
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}
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const link = document.createElement(`link`);
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link.setAttribute(`rel`, `prefetch`);
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link.setAttribute(`href`, url);
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Object.keys(options).forEach(key => {
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link.setAttribute(key, options[key]);
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});
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link.onload = resolve;
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link.onerror = reject;
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const parentElement = document.getElementsByTagName(`head`)[0] || document.getElementsByName(`script`)[0].parentNode;
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parentElement.appendChild(link);
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});
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};
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const xhrPrefetchStrategy = function (url) {
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return new Promise((resolve, reject) => {
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const req = new XMLHttpRequest();
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req.open(`GET`, url, true);
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req.onload = () => {
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if (req.status === 200) {
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resolve();
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} else {
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reject();
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}
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};
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req.send(null);
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});
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};
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const supportedPrefetchStrategy = support(`prefetch`) ? linkPrefetchStrategy : xhrPrefetchStrategy;
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const preFetched = {};
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const prefetch = function (url, options) {
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return new Promise(resolve => {
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if (preFetched[url]) {
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resolve();
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return;
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}
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supportedPrefetchStrategy(url, options).then(() => {
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resolve();
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preFetched[url] = true;
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}).catch(() => {}); // 404s are logged to the console anyway
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});
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};
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var _default = prefetch;
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exports.default = _default; |