astro/dist/assets/utils/vendor/image-size/detector.js

Astro is a modern site builder with web best practices, performance, and DX front-of-mind.

import { typeHandlers, types } from "./types/index.js";
// This map helps avoid validating for every single image type
const firstBytes = new Map([
	[0, "heif"],
	[56, "psd"],
	[66, "bmp"],
	[68, "dds"],
	[71, "gif"],
	[73, "tiff"],
	[77, "tiff"],
	[82, "webp"],
	[105, "icns"],
	[137, "png"],
	[255, "jpg"]
]);
export function detector(input) {
	const byte = input[0];
	const type = firstBytes.get(byte);
	if (type && typeHandlers.get(type).validate(input)) {
		return type;
	}
	return types.find((imageType) => typeHandlers.get(imageType).validate(input));
}