Differential D8055 Diff 29750 landing/use-pre-load-image-assets.react.js

Changeset View

Standalone View

	// @flow			// @flow

	import * as React from 'react';			import * as React from 'react';

	import { type Asset } from './asset-meta-data.js';			import { type ImageAsset } from './asset-meta-data.js';

	function usePreloadAssets(assets: Asset[]) {			function usePreloadImageAssets(assets: ImageAsset[]) {
	React.useEffect(() => {			React.useEffect(() => {
	const testWEBP = 'UklGRiIAAABXRUJQVlA4IBYAAAAwAQCdASoBAAEADsD+JaQAA3AAAAAA';			const testWEBP = 'UklGRiIAAABXRUJQVlA4IBYAAAAwAQCdASoBAAEADsD+JaQAA3AAAAAA';
	const testImg = new Image();			const testImg = new Image();

	// preload webp if supported			// preload webp if supported
	testImg.onload = () => {			testImg.onload = () => {
	for (const { url } of assets) {			for (const { url } of assets) {
	const image = new Image();			const image = new Image();
	image.src = `${url}.webp`;			image.src = `${url}.webp`;
	}			}
	};			};

	// preload png if webp not supported			// preload png if webp not supported
	testImg.onerror = () => {			testImg.onerror = () => {
	for (const { url } of assets) {			for (const { url } of assets) {
	const image = new Image();			const image = new Image();
	image.src = `${url}.png`;			image.src = `${url}.png`;
	}			}
	};			};

	testImg.src = `data:image/webp;base64,${testWEBP}`;			testImg.src = `data:image/webp;base64,${testWEBP}`;
	}, [assets]);			}, [assets]);
	}			}

	export default usePreloadAssets;			export default usePreloadImageAssets;