fetch で変換する

fetch(imageURL, {
	cf: {
		image: {
			fit: "scale-down",
			width: 800,
			height: 600,
		},
	},
});

export default {
	async fetch(request) {
		// If this request is coming from image resizing worker,
		// avoid causing an infinite loop by resizing it again:
		if (/image-resizing/.test(request.headers.get("via"))) {
			return fetch(request);
		}

		// Now you can safely use image resizing here
	},
};

const response = await fetch(imageURL, options);

if (response.ok || response.redirected) {
	// fetch() may respond with status 304
	return response;
} else {
	return Response.redirect(imageURL, 307);
}

const response = await fetch(imageURL, options);
if (response.ok || response.redirected) {
	return response;
} else {
	// Change to a URL on your server
	return fetch("https://img.example.com/blank-placeholder.png");
}

/**
 * Fetch and log a request
 * @param {Request} request
 */
export default {
	async fetch(request) {
		// Parse request URL to get access to query string
		let url = new URL(request.url);

		// Cloudflare-specific options are in the cf object.
		let options = { cf: { image: {} } };

		// Copy parameters from query string to request options.
		// You can implement various different parameters here.
		if (url.searchParams.has("fit"))
			options.cf.image.fit = url.searchParams.get("fit");
		if (url.searchParams.has("width"))
			options.cf.image.width = parseInt(url.searchParams.get("width"), 10);
		if (url.searchParams.has("height"))
			options.cf.image.height = parseInt(url.searchParams.get("height"), 10);
		if (url.searchParams.has("quality"))
			options.cf.image.quality = parseInt(url.searchParams.get("quality"), 10);

		// Your Worker is responsible for automatic format negotiation. Check the Accept header.
		const accept = request.headers.get("Accept");
		if (/image\/avif/.test(accept)) {
			options.cf.image.format = "avif";
		} else if (/image\/webp/.test(accept)) {
			options.cf.image.format = "webp";
		}

		// Get URL of the original (full size) image to resize.
		// You could adjust the URL here, e.g., prefix it with a fixed address of your server,
		// so that user-visible URLs are shorter and cleaner.
		const imageURL = url.searchParams.get("image");
		if (!imageURL)
			return new Response('Missing "image" value', { status: 400 });

		try {
			// TODO: Customize validation logic
			const { hostname, pathname } = new URL(imageURL);

			// Optionally, only allow URLs with JPEG, PNG, GIF, or WebP file extensions
			// @see https://developers.cloudflare.com/images/url-format#supported-formats-and-limitations
			if (!/\.(jpe?g|png|gif|webp)$/i.test(pathname)) {
				return new Response("Disallowed file extension", { status: 400 });
			}

			// Demo: Only accept "example.com" images
			if (hostname !== "example.com") {
				return new Response('Must use "example.com" source images', {
					status: 403,
				});
			}
		} catch (err) {
			return new Response('Invalid "image" value', { status: 400 });
		}

		// Build a request that passes through request headers
		const imageRequest = new Request(imageURL, {
			headers: request.headers,
		});

		// Returning fetch() with resizing options will pass through response with the resized image.
		return fetch(imageRequest, options);
	},
};