39 lines
1.2 KiB
JavaScript
39 lines
1.2 KiB
JavaScript
// Convenience function to load polyfills and return a promise when it's done.
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// If there are no polyfills, then this is just Promise.resolve() which means
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// it will execute in the same tick of the event loop (i.e. near-instant).
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function importBasePolyfills() {
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return import(/* webpackChunkName: "base_polyfills" */ './base_polyfills');
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}
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function importExtraPolyfills() {
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return import(/* webpackChunkName: "extra_polyfills" */ './extra_polyfills');
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}
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function loadPolyfills() {
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const needsBasePolyfills = !(
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window.Intl &&
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Object.assign &&
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Number.isNaN &&
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window.Symbol &&
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Array.prototype.includes
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);
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// Latest version of Firefox and Safari do not have IntersectionObserver.
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// Edge does not have requestIdleCallback and object-fit CSS property.
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// This avoids shipping them all the polyfills.
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const needsExtraPolyfills = !(
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window.IntersectionObserver &&
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window.IntersectionObserverEntry &&
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'isIntersecting' in IntersectionObserverEntry.prototype &&
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window.requestIdleCallback &&
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'object-fit' in (new Image()).style
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);
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return Promise.all([
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needsBasePolyfills && importBasePolyfills(),
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needsExtraPolyfills && importExtraPolyfills(),
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]);
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}
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export default loadPolyfills;
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